Pull args, intl, logging, shelf, and source_maps out of the SDK.

pkg/csslib/lib/src/tree.dart

Index: pkg/csslib/lib/src/tree.dart
diff --git a/pkg/csslib/lib/src/tree.dart b/pkg/csslib/lib/src/tree.dart
deleted file mode 100644
index 53a5f9f054fd181f337d92e12eeb50d9f27b66c8..0000000000000000000000000000000000000000
--- a/pkg/csslib/lib/src/tree.dart
+++ /dev/null
@@ -1,1406 +0,0 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-part of csslib.visitor;
-
-/////////////////////////////////////////////////////////////////////////
-// CSS specific types:
-/////////////////////////////////////////////////////////////////////////
-
-class Identifier extends TreeNode {
-  String name;
-
-  Identifier(this.name, SourceSpan span): super(span);
-
-  Identifier clone() => new Identifier(name, span);
-
-  visit(VisitorBase visitor) => visitor.visitIdentifier(this);
-
-  String toString() => name;
-}
-
-class Wildcard extends TreeNode {
-  Wildcard(SourceSpan span): super(span);
-  Wildcard clone() => new Wildcard(span);
-  visit(VisitorBase visitor) => visitor.visitWildcard(this);
-
-  String get name => '*';
-}
-
-class ThisOperator extends TreeNode {
-  ThisOperator(SourceSpan span): super(span);
-  ThisOperator clone() => new ThisOperator(span);
-  visit(VisitorBase visitor) => visitor.visitThisOperator(this);
-
-  String get name => '&';
-}
-
-class Negation extends TreeNode {
-  Negation(SourceSpan span): super(span);
-  Negation clone() => new Negation(span);
-  visit(VisitorBase visitor) => visitor.visitNegation(this);
-
-  String get name => 'not';
-}
-
-// /*  ....   */
-class CssComment extends TreeNode {
-  final String comment;
-
-  CssComment(this.comment, SourceSpan span): super(span);
-  CssComment clone() => new CssComment(comment, span);
-  visit(VisitorBase visitor) => visitor.visitCssComment(this);
-}
-
-// CDO/CDC (Comment Definition Open <!-- and Comment Definition Close -->).
-class CommentDefinition extends CssComment {
-  CommentDefinition(String comment, SourceSpan span): super(comment, span);
-  CommentDefinition clone() => new CommentDefinition(comment, span);
-  visit(VisitorBase visitor) => visitor.visitCommentDefinition(this);
-}
-
-class SelectorGroup extends TreeNode {
-  final List<Selector> selectors;
-
-  SelectorGroup(this.selectors, SourceSpan span): super(span);
-
-  SelectorGroup clone() => new SelectorGroup(selectors, span);
-
-  visit(VisitorBase visitor) => visitor.visitSelectorGroup(this);
-}
-
-class Selector extends TreeNode {
-  final List<SimpleSelectorSequence> simpleSelectorSequences;
-
-  Selector(this.simpleSelectorSequences, SourceSpan span) : super(span);
-
-  void add(SimpleSelectorSequence seq) => simpleSelectorSequences.add(seq);
-
-  int get length => simpleSelectorSequences.length;
-
-  Selector clone() {
-    var simpleSequences = simpleSelectorSequences
-        .map((ss) => ss.clone())
-        .toList();
-
-    return new Selector(simpleSequences, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitSelector(this);
-}
-
-class SimpleSelectorSequence extends TreeNode {
-  /** +, >, ~, NONE */
-  int combinator;
-  final SimpleSelector simpleSelector;
-
-  SimpleSelectorSequence(this.simpleSelector, SourceSpan span,
-      [int combinator = TokenKind.COMBINATOR_NONE])
-      : combinator = combinator, super(span);
-
-  bool get isCombinatorNone => combinator == TokenKind.COMBINATOR_NONE;
-  bool get isCombinatorPlus => combinator == TokenKind.COMBINATOR_PLUS;
-  bool get isCombinatorGreater => combinator == TokenKind.COMBINATOR_GREATER;
-  bool get isCombinatorTilde => combinator == TokenKind.COMBINATOR_TILDE;
-  bool get isCombinatorDescendant =>
-      combinator == TokenKind.COMBINATOR_DESCENDANT;
-
-  String get _combinatorToString =>
-      isCombinatorDescendant ? ' ' :
-          isCombinatorPlus ? ' + ' :
-              isCombinatorGreater ? ' > ' :
-                  isCombinatorTilde ? ' ~ ' : '';
-
-  SimpleSelectorSequence clone() =>
-      new SimpleSelectorSequence(simpleSelector, span, combinator);
-
-  visit(VisitorBase visitor) => visitor.visitSimpleSelectorSequence(this);
-
-  String toString() => simpleSelector.name;
-}
-
-/* All other selectors (element, #id, .class, attribute, pseudo, negation,
- * namespace, *) are derived from this selector.
- */
-abstract class SimpleSelector extends TreeNode {
-  final _name; // Wildcard, ThisOperator, Identifier, Negation, others?
-
-  SimpleSelector(this._name, SourceSpan span) : super(span);
-
-  String get name => _name.name;
-
-  bool get isWildcard => _name is Wildcard;
-
-  bool get isThis => _name is ThisOperator;
-
-  visit(VisitorBase visitor) => visitor.visitSimpleSelector(this);
-}
-
-// element name
-class ElementSelector extends SimpleSelector {
-  ElementSelector(name, SourceSpan span) : super(name, span);
-  visit(VisitorBase visitor) => visitor.visitElementSelector(this);
-
-  ElementSelector clone() => new ElementSelector(_name, span);
-
-  String toString() => name;
-}
-
-// namespace|element
-class NamespaceSelector extends SimpleSelector {
-  final _namespace;           // null, Wildcard or Identifier
-
-  NamespaceSelector(this._namespace, var name, SourceSpan span)
-      : super(name, span);
-
-  String get namespace =>
-      _namespace is Wildcard ? '*' : _namespace == null ? '' : _namespace.name;
-
-  bool get isNamespaceWildcard => _namespace is Wildcard;
-
-  SimpleSelector get nameAsSimpleSelector => _name;
-
-  NamespaceSelector clone() => new NamespaceSelector(_namespace, "", span);
-
-  visit(VisitorBase visitor) => visitor.visitNamespaceSelector(this);
-
-  String toString() => "$namespace|${nameAsSimpleSelector.name}";
-}
-
-// [attr op value]
-class AttributeSelector extends SimpleSelector {
-  final int _op;
-  final _value;
-
-  AttributeSelector(Identifier name, this._op, this._value,
-      SourceSpan span) : super(name, span);
-
-  int get operatorKind => _op;
-
-  get value => _value;
-
-  String matchOperator() {
-    switch (_op) {
-    case TokenKind.EQUALS:
-      return '=';
-    case TokenKind.INCLUDES:
-      return '~=';
-    case TokenKind.DASH_MATCH:
-      return '|=';
-    case TokenKind.PREFIX_MATCH:
-      return '^=';
-    case TokenKind.SUFFIX_MATCH:
-      return '\$=';
-    case TokenKind.SUBSTRING_MATCH:
-      return '*=';
-    case TokenKind.NO_MATCH:
-      return '';
-    }
-  }
-
-  // Return the TokenKind for operator used by visitAttributeSelector.
-  String matchOperatorAsTokenString() {
-    switch (_op) {
-    case TokenKind.EQUALS:
-      return 'EQUALS';
-    case TokenKind.INCLUDES:
-      return 'INCLUDES';
-    case TokenKind.DASH_MATCH:
-      return 'DASH_MATCH';
-    case TokenKind.PREFIX_MATCH:
-      return 'PREFIX_MATCH';
-    case TokenKind.SUFFIX_MATCH:
-      return 'SUFFIX_MATCH';
-    case TokenKind.SUBSTRING_MATCH:
-      return 'SUBSTRING_MATCH';
-    }
-  }
-
-  String valueToString() {
-    if (_value != null) {
-      if (_value is Identifier) {
-        return _value.name;
-      } else {
-        return '"${_value}"';
-      }
-    } else {
-      return '';
-    }
-  }
-
-  AttributeSelector clone() => new AttributeSelector(_name, _op, _value, span);
-
-  visit(VisitorBase visitor) => visitor.visitAttributeSelector(this);
-
-  String toString() => "[$name${matchOperator()}${valueToString()}]";
-}
-
-// #id
-class IdSelector extends SimpleSelector {
-  IdSelector(Identifier name, SourceSpan span) : super(name, span);
-  IdSelector clone() => new IdSelector(_name, span);
-  visit(VisitorBase visitor) => visitor.visitIdSelector(this);
-
-  String toString() => "#$_name";
-}
-
-// .class
-class ClassSelector extends SimpleSelector {
-  ClassSelector(Identifier name, SourceSpan span) : super(name, span);
-  ClassSelector clone() => new ClassSelector(_name, span);
-  visit(VisitorBase visitor) => visitor.visitClassSelector(this);
-
-  String toString() => ".$_name";
-}
-
-// :pseudoClass
-class PseudoClassSelector extends SimpleSelector {
-  PseudoClassSelector(Identifier name, SourceSpan span) : super(name, span);
-  visit(VisitorBase visitor) => visitor.visitPseudoClassSelector(this);
-
-  PseudoClassSelector clone() => new PseudoClassSelector(_name, span);
-
-  String toString() => ":$name";
-}
-
-// ::pseudoElement
-class PseudoElementSelector extends SimpleSelector {
-  PseudoElementSelector(Identifier name, SourceSpan span) : super(name, span);
-  visit(VisitorBase visitor) => visitor.visitPseudoElementSelector(this);
-
-  PseudoElementSelector clone() => new PseudoElementSelector(_name, span);
-
-  String toString() => "::$name";
-}
-
-// :pseudoClassFunction(expression)
-class PseudoClassFunctionSelector extends PseudoClassSelector {
-  final SelectorExpression expression;
-
-  PseudoClassFunctionSelector(Identifier name, this.expression, SourceSpan span)
-      : super(name, span);
-
-  PseudoClassFunctionSelector clone() =>
-      new PseudoClassFunctionSelector(_name, expression, span);
-
-  visit(VisitorBase visitor) =>
-      visitor.visitPseudoClassFunctionSelector(this);
-}
-
-// ::pseudoElementFunction(expression)
-class PseudoElementFunctionSelector extends PseudoElementSelector {
-  final SelectorExpression expression;
-
-  PseudoElementFunctionSelector(Identifier name, this.expression,
-          SourceSpan span)
-      : super(name, span);
-
-  PseudoElementFunctionSelector clone() =>
-      new PseudoElementFunctionSelector(_name, expression, span);
-
-  visit(VisitorBase visitor) =>
-      visitor.visitPseudoElementFunctionSelector(this);
-}
-
-class SelectorExpression extends TreeNode {
-  final List<Expression> expressions;
-
-  SelectorExpression(this.expressions, SourceSpan span): super(span);
-
-  SelectorExpression clone() {
-    return new SelectorExpression(
-        expressions.map((e) => e.clone()).toList(), span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitSelectorExpression(this);
-}
-
-// :NOT(negation_arg)
-class NegationSelector extends SimpleSelector {
-  final SimpleSelector negationArg;
-
-  NegationSelector(this.negationArg, SourceSpan span)
-      : super(new Negation(span), span);
-
-  NegationSelector clone() => new NegationSelector(negationArg, span);
-
-  visit(VisitorBase visitor) => visitor.visitNegationSelector(this);
-}
-
-class NoOp extends TreeNode {
-  NoOp() : super(null);
-
-  NoOp clone() => new NoOp();
-
-  visit(VisitorBase visitor) => visitor.visitNoOp(this);
-}
-
-class StyleSheet extends TreeNode {
-  /**
-   * Contains charset, ruleset, directives (media, page, etc.), and selectors.
-   */
-  final List<TreeNode> topLevels;
-
-  StyleSheet(this.topLevels, SourceSpan span) : super(span) {
-    for (final node in topLevels) {
-      assert(node is TopLevelProduction || node is Directive);
-    }
-  }
-
-  /** Selectors only in this tree. */
-  StyleSheet.selector(this.topLevels, SourceSpan span) : super(span);
-
-  StyleSheet clone() {
-    var clonedTopLevels = topLevels.map((e) => e.clone()).toList();
-    return new StyleSheet(clonedTopLevels, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitStyleSheet(this);
-}
-
-class TopLevelProduction extends TreeNode {
-  TopLevelProduction(SourceSpan span) : super(span);
-  TopLevelProduction clone() => new TopLevelProduction(span);
-  visit(VisitorBase visitor) => visitor.visitTopLevelProduction(this);
-}
-
-class RuleSet extends TopLevelProduction {
-  final SelectorGroup _selectorGroup;
-  final DeclarationGroup _declarationGroup;
-
-  RuleSet(this._selectorGroup, this._declarationGroup, SourceSpan span)
-      : super(span);
-
-  SelectorGroup get selectorGroup => _selectorGroup;
-  DeclarationGroup get declarationGroup => _declarationGroup;
-
-  RuleSet clone() {
-    var cloneSelectorGroup = _selectorGroup.clone();
-    var cloneDeclarationGroup = _declarationGroup.clone();
-    return new RuleSet(cloneSelectorGroup, cloneDeclarationGroup, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitRuleSet(this);
-}
-
-class Directive extends TreeNode {
-  Directive(SourceSpan span) : super(span);
-
-  bool get isBuiltIn => true;       // Known CSS directive?
-  bool get isExtension => false;    // SCSS extension?
-
-  Directive clone() => new Directive(span);
-  visit(VisitorBase visitor) => visitor.visitDirective(this);
-}
-
-class ImportDirective extends Directive {
-  /** import name specified. */
-  final String import;
-
-  /** Any media queries for this import. */
-  final List<MediaQuery> mediaQueries;
-
-  ImportDirective(this.import, this.mediaQueries, SourceSpan span)
-      : super(span);
-
-  ImportDirective clone() {
-    var cloneMediaQueries = [];
-    for (var mediaQuery in mediaQueries) {
-      cloneMediaQueries.add(mediaQuery.clone());
-    }
-    return new ImportDirective(import, cloneMediaQueries, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitImportDirective(this);
-}
-
-/**
- *  MediaExpression grammar:
- *    '(' S* media_feature S* [ ':' S* expr ]? ')' S*
- */
-class MediaExpression extends TreeNode {
-  final bool andOperator;
-  final Identifier _mediaFeature;
-  final Expressions exprs;
-
-  MediaExpression(this.andOperator, this._mediaFeature, this.exprs,
-          SourceSpan span)
-      : super(span);
-
-  String get mediaFeature => _mediaFeature.name;
-
-  MediaExpression clone() {
-    var clonedExprs = exprs.clone();
-    return new MediaExpression(andOperator, _mediaFeature, clonedExprs, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitMediaExpression(this);
-}
-
-/**
- * MediaQuery grammar:
- *    : [ONLY | NOT]? S* media_type S* [ AND S* media_expression ]*
- *    | media_expression [ AND S* media_expression ]*
- *   media_type
- *    : IDENT
- *   media_expression
- *    : '(' S* media_feature S* [ ':' S* expr ]? ')' S*
- *   media_feature
- *    : IDENT
- */
-class MediaQuery extends TreeNode {
-  /** not, only or no operator. */
-  final int _mediaUnary;
-  final Identifier _mediaType;
-  final List<MediaExpression> expressions;
-
-  MediaQuery(this._mediaUnary, this._mediaType, this.expressions,
-          SourceSpan span)
-      : super(span);
-
-  bool get hasMediaType => _mediaType != null;
-  String get mediaType => _mediaType.name;
-
-  bool get hasUnary => _mediaUnary != -1;
-  String get unary =>
-      TokenKind.idToValue(TokenKind.MEDIA_OPERATORS, _mediaUnary).toUpperCase();
-
-  MediaQuery clone() {
-    var cloneExpressions = [];
-    for (var expr in expressions) {
-      cloneExpressions.add(expr.clone());
-    }
-    return new MediaQuery(_mediaUnary, _mediaType, cloneExpressions, span);
-  }
-  visit(VisitorBase visitor) => visitor.visitMediaQuery(this);
-}
-
-class MediaDirective extends Directive {
-  final List<MediaQuery> mediaQueries;
-  final List<RuleSet> rulesets;
-
-  MediaDirective(this.mediaQueries, this.rulesets, SourceSpan span)
-      : super(span);
-
-  MediaDirective clone() {
-    var cloneQueries = [];
-    for (var mediaQuery in mediaQueries) {
-      cloneQueries.add(mediaQuery.clone());
-    }
-    var cloneRulesets = [];
-    for (var ruleset in rulesets) {
-      cloneRulesets.add(ruleset.clone());
-    }
-    return new MediaDirective(cloneQueries, cloneRulesets, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitMediaDirective(this);
-}
-
-class HostDirective extends Directive {
-  final List<RuleSet> rulesets;
-
-  HostDirective(this.rulesets, SourceSpan span) : super(span);
-
-  HostDirective clone() {
-    var cloneRulesets = [];
-    for (var ruleset in rulesets) {
-      cloneRulesets.add(ruleset.clone());
-    }
-    return new HostDirective(cloneRulesets, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitHostDirective(this);
-}
-
-class PageDirective extends Directive {
-  final String _ident;
-  final String _pseudoPage;
-  final List<DeclarationGroup> _declsMargin;
-
-  PageDirective(this._ident, this._pseudoPage, this._declsMargin,
-      SourceSpan span) : super(span);
-
-  PageDirective clone() {
-    var cloneDeclsMargin = [];
-    for (var declMargin in _declsMargin) {
-      cloneDeclsMargin.add(declMargin.clone());
-    }
-    return new PageDirective(_ident, _pseudoPage, cloneDeclsMargin, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitPageDirective(this);
-
-  bool get hasIdent => _ident != null && _ident.length > 0;
-  bool get hasPseudoPage => _pseudoPage != null && _pseudoPage.length > 0;
-}
-
-class CharsetDirective extends Directive {
-  final String charEncoding;
-
-  CharsetDirective(this.charEncoding, SourceSpan span) : super(span);
-  CharsetDirective clone() => new CharsetDirective(charEncoding, span);
-  visit(VisitorBase visitor) => visitor.visitCharsetDirective(this);
-}
-
-class KeyFrameDirective extends Directive {
-  /*
-   * Either @keyframe or keyframe prefixed with @-webkit-, @-moz-, @-ms-, @-o-.
-   */
-  final int _keyframeName;
-  final name;
-  final List<KeyFrameBlock> _blocks;
-
-  KeyFrameDirective(this._keyframeName, this.name, SourceSpan span)
-      : _blocks = [], super(span);
-
-  add(KeyFrameBlock block) {
-    _blocks.add(block);
-  }
-
-  String get keyFrameName {
-    switch (_keyframeName) {
-      case TokenKind.DIRECTIVE_KEYFRAMES:
-      case TokenKind.DIRECTIVE_MS_KEYFRAMES:
-        return '@keyframes';
-      case TokenKind.DIRECTIVE_WEB_KIT_KEYFRAMES: return '@-webkit-keyframes';
-      case TokenKind.DIRECTIVE_MOZ_KEYFRAMES: return '@-moz-keyframes';
-      case TokenKind.DIRECTIVE_O_KEYFRAMES: return '@-o-keyframes';
-    }
-  }
-
-  KeyFrameDirective clone() {
-    var cloneBlocks = [];
-    for (var block in _blocks) {
-      cloneBlocks.add(block.clone());
-    }
-    return new KeyFrameDirective(_keyframeName, cloneBlocks, span);
-  }
-  visit(VisitorBase visitor) => visitor.visitKeyFrameDirective(this);
-}
-
-class KeyFrameBlock extends Expression {
-  final Expressions _blockSelectors;
-  final DeclarationGroup _declarations;
-
-  KeyFrameBlock(this._blockSelectors, this._declarations, SourceSpan span)
-      : super(span);
-
-  KeyFrameBlock clone() =>
-      new KeyFrameBlock(_blockSelectors.clone(), _declarations.clone(), span);
-  visit(VisitorBase visitor) => visitor.visitKeyFrameBlock(this);
-}
-
-class FontFaceDirective extends Directive {
-  final DeclarationGroup _declarations;
-
-  FontFaceDirective(this._declarations, SourceSpan span) : super(span);
-
-  FontFaceDirective clone() =>
-      new FontFaceDirective(_declarations.clone(), span);
-  visit(VisitorBase visitor) => visitor.visitFontFaceDirective(this);
-}
-
-class StyletDirective extends Directive {
-  final String dartClassName;
-  final List<RuleSet> rulesets;
-
-  StyletDirective(this.dartClassName, this.rulesets, SourceSpan span)
-     : super(span);
-
-  bool get isBuiltIn => false;
-  bool get isExtension => true;
-
-  StyletDirective clone() {
-    var cloneRulesets = [];
-    for (var ruleset in rulesets) {
-      cloneRulesets.add(ruleset.clone());
-    }
-    return new StyletDirective(dartClassName, cloneRulesets, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitStyletDirective(this);
-}
-
-class NamespaceDirective extends Directive {
-  /** Namespace prefix. */
-  final String _prefix;
-
-  /** URI associated with this namespace. */
-  final String _uri;
-
-  NamespaceDirective(this._prefix, this._uri, SourceSpan span) : super(span);
-
-  NamespaceDirective clone() => new NamespaceDirective(_prefix, _uri, span);
-
-  visit(VisitorBase visitor) => visitor.visitNamespaceDirective(this);
-
-  String get prefix => _prefix.length > 0 ? '$_prefix ' : '';
-}
-
-/** To support Less syntax @name: expression */
-class VarDefinitionDirective extends Directive {
-  final VarDefinition def;
-
-  VarDefinitionDirective(this.def, SourceSpan span) : super(span);
-
-  VarDefinitionDirective clone() =>
-      new VarDefinitionDirective(def.clone(), span);
-
-  visit(VisitorBase visitor) => visitor.visitVarDefinitionDirective(this);
-}
-
-class MixinDefinition extends Directive {
-  final String name;
-  final List definedArgs;
-  final bool varArgs;
-
-  MixinDefinition(this.name, this.definedArgs, this.varArgs, SourceSpan span)
-      : super(span);
-
-  MixinDefinition clone() {
-    var cloneDefinedArgs = [];
-    for (var definedArg in definedArgs) {
-      cloneDefinedArgs.add(definedArg.clone());
-    }
-    return new MixinDefinition(name, cloneDefinedArgs, varArgs, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitMixinDefinition(this);
-}
-
-/** Support a Sass @mixin. See http://sass-lang.com for description. */
-class MixinRulesetDirective extends MixinDefinition {
-  final List<RuleSet> rulesets;
-
-  MixinRulesetDirective(String name, List<VarDefinitionDirective> args,
-      bool varArgs, this.rulesets, SourceSpan span) :
-      super(name, args, varArgs, span);
-
-  MixinRulesetDirective clone() {
-    var clonedArgs = [];
-    for (var arg in definedArgs) {
-      clonedArgs.add(arg.clone());
-    }
-    var clonedRulesets = [];
-    for (var ruleset in rulesets) {
-      clonedRulesets.add(ruleset.clone());
-    }
-    return new MixinRulesetDirective(name, clonedArgs, varArgs, clonedRulesets,
-        span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitMixinRulesetDirective(this);
-}
-
-class MixinDeclarationDirective extends MixinDefinition {
-  final DeclarationGroup declarations;
-
-  MixinDeclarationDirective(String name, List<VarDefinitionDirective>  args,
-      bool varArgs, this.declarations, SourceSpan span) :
-      super(name, args, varArgs, span);
-
-  MixinDeclarationDirective clone() {
-    var clonedArgs = [];
-    for (var arg in definedArgs) {
-      clonedArgs.add(arg.clone());
-    }
-    return new MixinDeclarationDirective(name, clonedArgs, varArgs,
-        declarations.clone(), span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitMixinDeclarationDirective(this);
-}
-
-/** To support consuming a SASS mixin @include. */
-class IncludeDirective extends Directive {
-  final String name;
-  final List<List<TreeNode>> args;
-
-  IncludeDirective(this.name, this.args, SourceSpan span) : super(span);
-
-  IncludeDirective clone() {
-    var cloneArgs = [];
-    for (var arg in args) {
-      for (var term in arg) {
-        cloneArgs.add(term.clone());
-      }
-    }
-    return new IncludeDirective(name, cloneArgs, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitIncludeDirective(this);
-}
-
-/** To support SASS @content. */
-class ContentDirective extends Directive {
-  ContentDirective(SourceSpan span) : super(span);
-
-  visit(VisitorBase visitor) => visitor.visitContentDirective(this);
-}
-
-class Declaration extends TreeNode {
-  final Identifier _property;
-  final Expression _expression;
-  /** Style exposed to Dart. */
-  dynamic dartStyle;
-  final bool important;
-
-  /**
-   * IE CSS hacks that can only be read by a particular IE version.
-   *   7 implies IE 7 or older property (e.g., *background: blue;)
-   *   Note:  IE 8 or older property (e.g., background: green\9;) is handled
-   *          by IE8Term in declaration expression handling.
-   *   Note:  IE 6 only property with a leading underscore is a valid IDENT
-   *          since an ident can start with underscore (e.g., _background: red;)
-   */
-  final bool isIE7;
-
-  Declaration(this._property, this._expression, this.dartStyle, SourceSpan span,
-              {important: false, ie7: false})
-      : this.important = important, this.isIE7 = ie7, super(span);
-
-  String get property => isIE7 ? '*${_property.name}' : _property.name;
-  Expression get expression => _expression;
-
-  bool get hasDartStyle => dartStyle != null;
-
-  Declaration clone() =>
-      new Declaration(_property.clone(), _expression.clone(), dartStyle, span,
-      important: important);
-
-  visit(VisitorBase visitor) => visitor.visitDeclaration(this);
-}
-
-// TODO(terry): Consider 2 kinds of VarDefinitions static at top-level and
-//              dynamic when in a declaration.  Currently, Less syntax
-//              '@foo: expression' and 'var-foo: expression' in a declaration
-//              are statically resolved. Better solution, if @foo or var-foo
-//              are top-level are then statically resolved and var-foo in a
-//              declaration group (surrounded by a selector) would be dynamic.
-class VarDefinition extends Declaration {
-  bool badUsage = false;
-
-  VarDefinition(Identifier definedName, Expression expr, SourceSpan span)
-      : super(definedName, expr, null, span);
-
-  String get definedName => _property.name;
-
-  VarDefinition clone() =>
-      new VarDefinition(_property.clone(),
-      expression != null ? expression.clone() : null, span);
-
-  visit(VisitorBase visitor) => visitor.visitVarDefinition(this);
-}
-
-/**
- * Node for usage of @include mixin[(args,...)] found in a declaration group
- * instead of at a ruleset (toplevel) e.g.,
- * div {
- *   @include mixin1;
- * }
- */
-class IncludeMixinAtDeclaration extends Declaration {
-  final IncludeDirective include;
-
-  IncludeMixinAtDeclaration(this.include, SourceSpan span)
-      : super(null, null, null, span);
-
-  IncludeMixinAtDeclaration clone() =>
-      new IncludeMixinAtDeclaration(include.clone(), span);
-
-  visit(VisitorBase visitor) =>
-      visitor.visitIncludeMixinAtDeclaration(this);
-}
-
-class ExtendDeclaration extends Declaration {
-  final List<TreeNode> selectors;
-
-  ExtendDeclaration(this.selectors, SourceSpan span) :
-      super(null, null, null, span);
-
-  ExtendDeclaration clone() {
-    var newSelector = selectors.map((s) => s.clone()).toList();
-    return new ExtendDeclaration(newSelector, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitExtendDeclaration(this);
-}
-
-class DeclarationGroup extends TreeNode {
-  /** Can be either Declaration or RuleSet (if nested selector). */
-  final List declarations;
-
-  DeclarationGroup(this.declarations, SourceSpan span) : super(span);
-
-  DeclarationGroup clone() {
-    var clonedDecls = declarations.map((d) => d.clone()).toList();
-    return new DeclarationGroup(clonedDecls, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitDeclarationGroup(this);
-}
-
-class MarginGroup extends DeclarationGroup {
-  final int margin_sym;       // TokenType for for @margin sym.
-
-  MarginGroup(this.margin_sym, List<Declaration> decls, SourceSpan span)
-      : super(decls, span);
-  MarginGroup clone() =>
-    new MarginGroup(margin_sym, super.clone() as dynamic, span);
-  visit(VisitorBase visitor) => visitor.visitMarginGroup(this);
-}
-
-class VarUsage extends Expression {
-  final String name;
-  final List<Expression> defaultValues;
-
-  VarUsage(this.name, this.defaultValues, SourceSpan span) : super(span);
-
-  VarUsage clone() {
-    var clonedValues = [];
-    for (var expr in defaultValues) {
-      clonedValues.add(expr.clone());
-    }
-    return new VarUsage(name, clonedValues, span);
-  }
-
-  visit(VisitorBase visitor) => visitor.visitVarUsage(this);
-}
-
-class OperatorSlash extends Expression {
-  OperatorSlash(SourceSpan span) : super(span);
-  OperatorSlash clone() => new OperatorSlash(span);
-  visit(VisitorBase visitor) => visitor.visitOperatorSlash(this);
-}
-
-class OperatorComma extends Expression {
-  OperatorComma(SourceSpan span) : super(span);
-  OperatorComma clone() => new OperatorComma(span);
-  visit(VisitorBase visitor) => visitor.visitOperatorComma(this);
-}
-
-class OperatorPlus extends Expression {
-  OperatorPlus(SourceSpan span) : super(span);
-  OperatorPlus clone() => new OperatorPlus(span);
-  visit(VisitorBase visitor) => visitor.visitOperatorPlus(this);
-}
-
-class OperatorMinus extends Expression {
-  OperatorMinus(SourceSpan span) : super(span);
-  OperatorMinus clone() => new OperatorMinus(span);
-  visit(VisitorBase visitor) => visitor.visitOperatorMinus(this);
-}
-
-class UnicodeRangeTerm extends Expression {
-  final String first;
-  final String second;
-
-  UnicodeRangeTerm(this.first, this.second, SourceSpan span) : super(span);
-
-  bool get hasSecond => second != null;
-
-  UnicodeRangeTerm clone() => new UnicodeRangeTerm(first, second, span);
-
-  visit(VisitorBase visitor) => visitor.visitUnicodeRangeTerm(this);
-}
-
-class LiteralTerm extends Expression {
-  // TODO(terry): value and text fields can be made final once all CSS resources
-  //              are copied/symlink'd in the build tool and UriVisitor in
-  //              web_ui is removed.
-  dynamic value;
-  String text;
-
-  LiteralTerm(this.value, this.text, SourceSpan span) : super(span);
-
-  LiteralTerm clone() => new LiteralTerm(value, text, span);
-
-  visit(VisitorBase visitor) => visitor.visitLiteralTerm(this);
-}
-
-class NumberTerm extends LiteralTerm {
-  NumberTerm(value, String t, SourceSpan span) : super(value, t, span);
-  NumberTerm clone() => new NumberTerm(value, text, span);
-  visit(VisitorBase visitor) => visitor.visitNumberTerm(this);
-}
-
-class UnitTerm extends LiteralTerm {
-  final int unit;
-
-  UnitTerm(value, String t, SourceSpan span, this.unit) : super(value, t, span);
-
-  UnitTerm clone() => new UnitTerm(value, text, span, unit);
-
-  visit(VisitorBase visitor) => visitor.visitUnitTerm(this);
-
-  String unitToString() => TokenKind.unitToString(unit);
-
-  String toString() => '$text${unitToString()}';
-}
-
-class LengthTerm extends UnitTerm {
-  LengthTerm(value, String t, SourceSpan span,
-      [int unit = TokenKind.UNIT_LENGTH_PX]) : super(value, t, span, unit) {
-    assert(this.unit == TokenKind.UNIT_LENGTH_PX ||
-        this.unit == TokenKind.UNIT_LENGTH_CM ||
-        this.unit == TokenKind.UNIT_LENGTH_MM ||
-        this.unit == TokenKind.UNIT_LENGTH_IN ||
-        this.unit == TokenKind.UNIT_LENGTH_PT ||
-        this.unit == TokenKind.UNIT_LENGTH_PC);
-  }
-  LengthTerm clone() => new LengthTerm(value, text, span, unit);
-  visit(VisitorBase visitor) => visitor.visitLengthTerm(this);
-}
-
-class PercentageTerm extends LiteralTerm {
-  PercentageTerm(value, String t, SourceSpan span) : super(value, t, span);
-  PercentageTerm clone() => new PercentageTerm(value, text, span);
-  visit(VisitorBase visitor) => visitor.visitPercentageTerm(this);
-}
-
-class EmTerm extends LiteralTerm {
-  EmTerm(value, String t, SourceSpan span) : super(value, t, span);
-  EmTerm clone() => new EmTerm(value, text, span);
-  visit(VisitorBase visitor) => visitor.visitEmTerm(this);
-}
-
-class ExTerm extends LiteralTerm {
-  ExTerm(value, String t, SourceSpan span) : super(value, t, span);
-  ExTerm clone() => new ExTerm(value, text, span);
-  visit(VisitorBase visitor) => visitor.visitExTerm(this);
-}
-
-class AngleTerm extends UnitTerm {
-  AngleTerm(var value, String t, SourceSpan span,
-    [int unit = TokenKind.UNIT_LENGTH_PX]) : super(value, t, span, unit) {
-    assert(this.unit == TokenKind.UNIT_ANGLE_DEG ||
-        this.unit == TokenKind.UNIT_ANGLE_RAD ||
-        this.unit == TokenKind.UNIT_ANGLE_GRAD ||
-        this.unit == TokenKind.UNIT_ANGLE_TURN);
-  }
-
-  AngleTerm clone() => new AngleTerm(value, text, span, unit);
-  visit(VisitorBase visitor) => visitor.visitAngleTerm(this);
-}
-
-class TimeTerm extends UnitTerm {
-  TimeTerm(var value, String t, SourceSpan span,
-    [int unit = TokenKind.UNIT_LENGTH_PX]) : super(value, t, span, unit) {
-    assert(this.unit == TokenKind.UNIT_ANGLE_DEG ||
-        this.unit == TokenKind.UNIT_TIME_MS ||
-        this.unit == TokenKind.UNIT_TIME_S);
-  }
-
-  TimeTerm clone() => new TimeTerm(value, text, span, unit);
-  visit(VisitorBase visitor) => visitor.visitTimeTerm(this);
-}
-
-class FreqTerm extends UnitTerm {
-  FreqTerm(var value, String t, SourceSpan span,
-    [int unit = TokenKind.UNIT_LENGTH_PX]) : super(value, t, span, unit) {
-    assert(unit == TokenKind.UNIT_FREQ_HZ || unit == TokenKind.UNIT_FREQ_KHZ);
-  }
-
-  FreqTerm clone() => new FreqTerm(value, text, span, unit);
-  visit(VisitorBase visitor) => visitor.visitFreqTerm(this);
-}
-
-class FractionTerm extends LiteralTerm {
-  FractionTerm(var value, String t, SourceSpan span) : super(value, t, span);
-
-  FractionTerm clone() => new FractionTerm(value, text, span);
-  visit(VisitorBase visitor) => visitor.visitFractionTerm(this);
-}
-
-class UriTerm extends LiteralTerm {
-  UriTerm(String value, SourceSpan span) : super(value, value, span);
-
-  UriTerm clone() => new UriTerm(value, span);
-  visit(VisitorBase visitor) => visitor.visitUriTerm(this);
-}
-
-class ResolutionTerm extends UnitTerm {
-  ResolutionTerm(var value, String t, SourceSpan span,
-    [int unit = TokenKind.UNIT_LENGTH_PX]) : super(value, t, span, unit) {
-    assert(unit == TokenKind.UNIT_RESOLUTION_DPI ||
-        unit == TokenKind.UNIT_RESOLUTION_DPCM ||
-        unit == TokenKind.UNIT_RESOLUTION_DPPX);
-  }
-
-  ResolutionTerm clone() => new ResolutionTerm(value, text, span, unit);
-  visit(VisitorBase visitor) => visitor.visitResolutionTerm(this);
-}
-
-class ChTerm extends UnitTerm {
-  ChTerm(var value, String t, SourceSpan span,
-    [int unit = TokenKind.UNIT_LENGTH_PX]) : super(value, t, span, unit) {
-    assert(unit == TokenKind.UNIT_CH);
-  }
-
-  ChTerm clone() => new ChTerm(value, text, span, unit);
-  visit(VisitorBase visitor) => visitor.visitChTerm(this);
-}
-
-class RemTerm extends UnitTerm {
-  RemTerm(var value, String t, SourceSpan span,
-    [int unit = TokenKind.UNIT_LENGTH_PX]) : super(value, t, span, unit) {
-    assert(unit == TokenKind.UNIT_REM);
-  }
-
-  RemTerm clone() => new RemTerm(value, text, span, unit);
-  visit(VisitorBase visitor) => visitor.visitRemTerm(this);
-}
-
-class ViewportTerm extends UnitTerm {
-  ViewportTerm(var value, String t, SourceSpan span,
-    [int unit = TokenKind.UNIT_LENGTH_PX]) : super(value, t, span, unit) {
-    assert(unit == TokenKind.UNIT_VIEWPORT_VW ||
-        unit == TokenKind.UNIT_VIEWPORT_VH ||
-        unit == TokenKind.UNIT_VIEWPORT_VMIN ||
-        unit == TokenKind.UNIT_VIEWPORT_VMAX);
-  }
-
-  ViewportTerm clone() => new ViewportTerm(value, text, span, unit);
-  visit(VisitorBase visitor) => visitor.visitViewportTerm(this);
-}
-
-/** Type to signal a bad hex value for HexColorTerm.value. */
-class BAD_HEX_VALUE { }
-
-class HexColorTerm extends LiteralTerm {
-  HexColorTerm(var value, String t, SourceSpan span) : super(value, t, span);
-
-  HexColorTerm clone() => new HexColorTerm(value, text, span);
-  visit(VisitorBase visitor) => visitor.visitHexColorTerm(this);
-}
-
-class FunctionTerm extends LiteralTerm {
-  final Expressions _params;
-
-  FunctionTerm(var value, String t, this._params, SourceSpan span)
-      : super(value, t, span);
-
-  FunctionTerm clone() => new FunctionTerm(value, text, _params.clone(), span);
-  visit(VisitorBase visitor) => visitor.visitFunctionTerm(this);
-}
-
-/**
- * A "\9" was encountered at the end of the expression and before a semi-colon.
- * This is an IE trick to ignore a property or value except by IE 8 and older
- * browsers.
- */
-class IE8Term extends LiteralTerm {
-  IE8Term(SourceSpan span) : super('\\9', '\\9', span);
-  IE8Term clone() => new IE8Term(span);
-  visit(VisitorBase visitor) => visitor.visitIE8Term(this);
-}
-
-class GroupTerm extends Expression {
-  final List<LiteralTerm> _terms;
-
-  GroupTerm(SourceSpan span) : _terms =  [], super(span);
-
-  void add(LiteralTerm term) {
-    _terms.add(term);
-  }
-
-  GroupTerm clone() => new GroupTerm(span);
-  visit(VisitorBase visitor) => visitor.visitGroupTerm(this);
-}
-
-class ItemTerm extends NumberTerm {
-  ItemTerm(var value, String t, SourceSpan span) : super(value, t, span);
-
-  ItemTerm clone() => new ItemTerm(value, text, span);
-  visit(VisitorBase visitor) => visitor.visitItemTerm(this);
-}
-
-class Expressions extends Expression {
-  final List<Expression> expressions = [];
-
-  Expressions(SourceSpan span): super(span);
-
-  void add(Expression expression) {
-    expressions.add(expression);
-  }
-
-  Expressions clone() {
-    var clonedExprs = new Expressions(span);
-    for (var expr in expressions) {
-      clonedExprs.add(expr.clone());
-    }
-    return clonedExprs;
-  }
-  visit(VisitorBase visitor) => visitor.visitExpressions(this);
-}
-
-class BinaryExpression extends Expression {
-  final Token op;
-  final Expression x;
-  final Expression y;
-
-  BinaryExpression(this.op, this.x, this.y, SourceSpan span): super(span);
-
-  BinaryExpression clone() =>
-      new BinaryExpression(op, x.clone(), y.clone(), span);
-  visit(VisitorBase visitor) => visitor.visitBinaryExpression(this);
-}
-
-class UnaryExpression extends Expression {
-  final Token op;
-  final Expression self;
-
-  UnaryExpression(this.op, this.self, SourceSpan span): super(span);
-
-  UnaryExpression clone() => new UnaryExpression(op, self.clone(), span);
-  visit(VisitorBase visitor) => visitor.visitUnaryExpression(this);
-}
-
-abstract class DartStyleExpression extends TreeNode {
-  static const int unknownType = 0;
-  static const int fontStyle = 1;
-  static const int marginStyle = 2;
-  static const int borderStyle = 3;
-  static const int paddingStyle = 4;
-  static const int heightStyle = 5;
-  static const int widthStyle = 6;
-
-  final int _styleType;
-  int priority;
-
-  DartStyleExpression(this._styleType, SourceSpan span) : super(span);
-
-  /*
-   * Merges give 2 DartStyleExpression (or derived from DartStyleExpression,
-   * e.g., FontExpression, etc.) will merge if the two expressions are of the
-   * same property name (implies same exact type e.g, FontExpression).
-   */
-  merged(DartStyleExpression newDartExpr);
-
-  bool get isUnknown => _styleType == 0 || _styleType == null;
-  bool get isFont => _styleType == fontStyle;
-  bool get isMargin => _styleType == marginStyle;
-  bool get isBorder => _styleType == borderStyle;
-  bool get isPadding => _styleType == paddingStyle;
-  bool get isHeight => _styleType == heightStyle;
-  bool get isWidth => _styleType == widthStyle;
-  bool get isBoxExpression => isMargin || isBorder || isPadding;
-
-  bool isSame(DartStyleExpression other) => this._styleType == other._styleType;
-
-  visit(VisitorBase visitor) => visitor.visitDartStyleExpression(this);
-}
-
-class FontExpression extends DartStyleExpression {
-  final Font font;
-
-  //   font-style font-variant font-weight font-size/line-height font-family
-  // TODO(terry): Only px/pt for now need to handle all possible units to
-  //              support calc expressions on units.
-  FontExpression(SourceSpan span, {dynamic size, List<String> family,
-      int weight, String style, String variant, LineHeight lineHeight}) :
-        font = new Font(size : size is LengthTerm ? size.value : size,
-            family: family, weight: weight, style: style, variant: variant,
-            lineHeight: lineHeight),
-        super(DartStyleExpression.fontStyle, span);
-
-  FontExpression merged(FontExpression newFontExpr) {
-    if (this.isFont && newFontExpr.isFont) {
-      return new FontExpression.merge(this, newFontExpr);
-    }
-
-    return null;
-  }
-
-  /**
-   * Merge the two FontExpression and return the result.
-   */
-  factory FontExpression.merge(FontExpression x, FontExpression y) {
-    return new FontExpression._merge(x, y, y.span);
-  }
-
-  FontExpression._merge(FontExpression x, FontExpression y, SourceSpan span)
-      : super(DartStyleExpression.fontStyle, span),
-        font = new Font.merge(x.font, y.font);
-
-  FontExpression clone() =>
-    new FontExpression(span, size: font.size, family: font.family,
-        weight: font.weight, style: font.style, variant: font.variant,
-        lineHeight: font.lineHeight);
-
-  visit(VisitorBase visitor) => visitor.visitFontExpression(this);
-}
-
-abstract class BoxExpression extends DartStyleExpression {
-  final BoxEdge box;
-
-  BoxExpression(int styleType, SourceSpan span, this.box)
-      : super(styleType, span);
-
-  /*
-   * Merges give 2 DartStyleExpression (or derived from DartStyleExpression,
-   * e.g., FontExpression, etc.) will merge if the two expressions are of the
-   * same property name (implies same exact type e.g, FontExpression).
-   */
-  merged(BoxExpression newDartExpr);
-
-  visit(VisitorBase visitor) => visitor.visitBoxExpression(this);
-
-  String get formattedBoxEdge {
-    if (box.top == box.left && box.top == box.bottom &&
-        box.top== box.right) {
-      return '.uniform(${box.top})';
-    } else {
-      var left = box.left == null ? 0 : box.left;
-      var top = box.top == null ? 0 : box.top;
-      var right = box.right == null ? 0 : box.right;
-      var bottom = box.bottom == null ? 0 : box.bottom;
-      return '.clockwiseFromTop($top,$right,$bottom,$left)';
-    }
-  }
-}
-
-class MarginExpression extends BoxExpression {
-  // TODO(terry): Does auto for margin need to be exposed to Dart UI framework?
-  /** Margin expression ripped apart. */
-  MarginExpression(SourceSpan span, {num top, num right, num bottom, num left})
-      : super(DartStyleExpression.marginStyle, span,
-              new BoxEdge(left, top, right, bottom));
-
-  MarginExpression.boxEdge(SourceSpan span, BoxEdge box)
-      : super(DartStyleExpression.marginStyle, span, box);
-
-  merged(MarginExpression newMarginExpr) {
-    if (this.isMargin && newMarginExpr.isMargin) {
-      return new MarginExpression.merge(this, newMarginExpr);
-    }
-
-    return null;
-  }
-
-  /**
-   * Merge the two MarginExpressions and return the result.
-   */
-  factory MarginExpression.merge(MarginExpression x, MarginExpression y) {
-    return new MarginExpression._merge(x, y, y.span);
-  }
-
-  MarginExpression._merge(MarginExpression x, MarginExpression y,
-          SourceSpan span)
-      : super(x._styleType, span, new BoxEdge.merge(x.box, y.box));
-
-  MarginExpression clone() =>
-      new MarginExpression(span, top: box.top, right: box.right,
-      bottom: box.bottom, left: box.left);
-
-  visit(VisitorBase visitor) => visitor.visitMarginExpression(this);
-}
-
-class BorderExpression extends BoxExpression {
-  /** Border expression ripped apart. */
-  BorderExpression(SourceSpan span, {num top, num right, num bottom, num left})
-      : super(DartStyleExpression.borderStyle, span,
-              new BoxEdge(left, top, right, bottom));
-
-  BorderExpression.boxEdge(SourceSpan span, BoxEdge box)
-      : super(DartStyleExpression.borderStyle, span, box);
-
-  merged(BorderExpression newBorderExpr) {
-    if (this.isBorder && newBorderExpr.isBorder) {
-      return new BorderExpression.merge(this, newBorderExpr);
-    }
-
-    return null;
-  }
-
-  /**
-   * Merge the two BorderExpression and return the result.
-   */
-  factory BorderExpression.merge(BorderExpression x, BorderExpression y) {
-    return new BorderExpression._merge(x, y, y.span);
-  }
-
-  BorderExpression._merge(BorderExpression x, BorderExpression y,
-      SourceSpan span)
-      : super(DartStyleExpression.borderStyle, span,
-              new BoxEdge.merge(x.box, y.box));
-
-  BorderExpression clone() =>
-      new BorderExpression(span, top: box.top, right: box.right,
-      bottom: box.bottom, left: box.left);
-
-  visit(VisitorBase visitor) => visitor.visitBorderExpression(this);
-}
-
-class HeightExpression extends DartStyleExpression {
-  final height;
-
-  HeightExpression(SourceSpan span, this.height)
-      : super(DartStyleExpression.heightStyle, span);
-
-  merged(HeightExpression newHeightExpr) {
-    if (this.isHeight && newHeightExpr.isHeight) {
-      return newHeightExpr;
-    }
-
-    return null;
-  }
-
-  HeightExpression clone() => new HeightExpression(span, height);
-  visit(VisitorBase visitor) => visitor.visitHeightExpression(this);
-}
-
-class WidthExpression extends DartStyleExpression {
-  final width;
-
-  WidthExpression(SourceSpan span, this.width)
-      : super(DartStyleExpression.widthStyle, span);
-
-  merged(WidthExpression newWidthExpr) {
-    if (this.isWidth && newWidthExpr.isWidth) {
-      return newWidthExpr;
-    }
-
-    return null;
-  }
-
-  WidthExpression clone() => new WidthExpression(span, width);
-  visit(VisitorBase visitor) => visitor.visitWidthExpression(this);
-}
-
-class PaddingExpression extends BoxExpression {
-  /** Padding expression ripped apart. */
-  PaddingExpression(SourceSpan span, {num top, num right, num bottom, num left})
-      : super(DartStyleExpression.paddingStyle, span,
-              new BoxEdge(left, top, right, bottom));
-
-  PaddingExpression.boxEdge(SourceSpan span, BoxEdge box)
-      : super(DartStyleExpression.paddingStyle, span, box);
-
-  merged(PaddingExpression newPaddingExpr) {
-    if (this.isPadding && newPaddingExpr.isPadding) {
-      return new PaddingExpression.merge(this, newPaddingExpr);
-    }
-
-    return null;
-  }
-
-  /**
-   * Merge the two PaddingExpression and return the result.
-   */
-  factory PaddingExpression.merge(PaddingExpression x, PaddingExpression y) {
-    return new PaddingExpression._merge(x, y, y.span);
-  }
-
-  PaddingExpression._merge(PaddingExpression x, PaddingExpression y,
-          SourceSpan span)
-      : super(DartStyleExpression.paddingStyle, span,
-            new BoxEdge.merge(x.box, y.box));
-
-  PaddingExpression clone() =>
-      new PaddingExpression(span, top: box.top, right: box.right,
-      bottom: box.bottom, left: box.left);
-  visit(VisitorBase visitor) => visitor.visitPaddingExpression(this);
-}