Introduce getPrefixEndToken to avoid too big context in messages.

pkg/compiler/lib/src/tree/nodes.dart

 // 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 tree;
 
 abstract class Visitor<R> {
   const Visitor();
 
   R visitNode(Node node);
@@ skipping 129 matching lines @@
    * Returns Xml-like tree representation of this node.
    */
   toDebugString() {
     return PrettyPrinter.prettyPrint(this);
   }
 
   String getObjectDescription() => super.toString();
 
   Token getBeginToken();
 
+  /// Returns the token that ends the 'prefix' of this node.
+  ///
+  /// For instance the end of the parameters in a [FunctionExpression] or the
+  /// last token before the start of a class body for a [ClassNode].
+  Token getPrefixEndToken() => getEndToken();
+
   Token getEndToken();
 
   Assert asAssert() => null;
   AsyncModifier asAsyncModifier() => null;
   Await asAwait() => null;
   Block asBlock() => null;
   BreakStatement asBreakStatement() => null;
   Cascade asCascade() => null;
   CascadeReceiver asCascadeReceiver() => null;
   CaseMatch asCaseMatch() => null;
@@ skipping 96 matching lines @@
   visitChildren(Visitor visitor) {
     if (name != null) name.accept(visitor);
     if (typeParameters != null) typeParameters.accept(visitor);
     if (superclass != null) superclass.accept(visitor);
     if (interfaces != null) interfaces.accept(visitor);
     if (body != null) body.accept(visitor);
   }
 
   Token getBeginToken() => beginToken;
 
+  @override
+  Token getPrefixEndToken() {
+    Token token;
+    if (interfaces != null) {
+      token = interfaces.getEndToken();
+    }
+    if (token == null && superclass != null) {
+      token = superclass.getEndToken();
+    }
+    if (token == null && typeParameters != null) {
+      token == typeParameters.getEndToken();
+    }
+    if (token == null) {
+      token = name.getEndToken();
+    }
+    assert(invariant(beginToken, token != null));
+    return token;
+  }
+
   Token getEndToken() => endToken;
 }
 
 class MixinApplication extends Node {
   final TypeAnnotation superclass;
   final NodeList mixins;
 
   MixinApplication(this.superclass, this.mixins);
 
   MixinApplication asMixinApplication() => this;
@@ skipping 455 matching lines @@
 
   FunctionDeclaration(this.function);
 
   FunctionDeclaration asFunctionDeclaration() => this;
 
   accept(Visitor visitor) => visitor.visitFunctionDeclaration(this);
 
   visitChildren(Visitor visitor) => function.accept(visitor);
 
   Token getBeginToken() => function.getBeginToken();
+
+  @override
+  Token getPrefixEndToken() => function.getPrefixEndToken();
+
   Token getEndToken() => function.getEndToken();
 }
 
 /// Node representing the method implementation modifiers `sync*`, `async`, and
 /// `async*` or the invalid modifier `sync`.
 class AsyncModifier extends Node {
   /// The `async` or `sync` token.
   final Token asyncToken;
 
   /// The `*` token.
@@ skipping 68 matching lines @@
     return block.statements.isEmpty;
   }
 
   Token getBeginToken() {
     Token token = firstBeginToken(modifiers, returnType);
     if (token != null) return token;
     if (getOrSet != null) return getOrSet;
     return firstBeginToken(name, parameters);
   }
 
+  @override
+  Token getPrefixEndToken() {
+    return parameters != null ? parameters.getEndToken() : name.getEndToken();
+  }
+
   Token getEndToken() {
     Token token = (body == null) ? null : body.getEndToken();
     token = (token == null) ? parameters.getEndToken() : token;
     return (token == null) ? name.getEndToken() : token;
   }
 }
 
 typedef void DecodeErrorHandler(Token token, var error);
 
 abstract class Literal<T> extends Expression {
@@ skipping 454 matching lines @@
 
   accept(Visitor visitor) => visitor.visitTypeAnnotation(this);
 
   visitChildren(Visitor visitor) {
     typeName.accept(visitor);
     if (typeArguments != null) typeArguments.accept(visitor);
   }
 
   Token getBeginToken() => typeName.getBeginToken();
 
-  Token getEndToken() => typeName.getEndToken();
+  Token getEndToken() {
+    if (typeArguments != null) return typeArguments.getEndToken();
+    return typeName.getEndToken();
+  }
 }
 
 class TypeVariable extends Node {
   final Identifier name;
   final TypeAnnotation bound;
   TypeVariable(Identifier this.name, TypeAnnotation this.bound);
 
   accept(Visitor visitor) => visitor.visitTypeVariable(this);
 
   visitChildren(Visitor visitor) {
@@ skipping 1130 matching lines @@
 
   // VariableDefinitions.
   get metadata => null;
   get type => null;
 
   // Typedef.
   get typeParameters => null;
   get formals => null;
   get typedefKeyword => null;
 }