Revert "Remove Registry from registerMetadataConstant" and "Serialize metadata"

pkg/compiler/lib/src/js_backend/constant_handler_javascript.dart

 // Copyright (c) 2014, 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 js_backend;
 
 /// [ConstantCompilerTask] for compilation of constants for the JavaScript
 /// backend.
 ///
 /// Since this task needs to distinguish between frontend and backend constants
@@ skipping 97 matching lines @@
   final Set<ConstantValue> compiledConstants = new Set<ConstantValue>();
 
   // TODO(johnniwinther): Move this to the backend constant handler.
   /** Caches the statics where the initial value cannot be eagerly compiled. */
   final Set<VariableElement> lazyStatics = new Set<VariableElement>();
 
   // Constants computed for constant expressions.
   final Map<Node, ConstantExpression> nodeConstantMap =
       new Map<Node, ConstantExpression>();
 
+  // Constants computed for metadata.
+  final Map<MetadataAnnotation, ConstantExpression> metadataConstantMap =
+      new Map<MetadataAnnotation, ConstantExpression>();
+
   JavaScriptConstantCompiler(Compiler compiler)
       : super(compiler, JAVA_SCRIPT_CONSTANT_SYSTEM);
 
   ConstantExpression compileVariableWithDefinitions(
       VariableElement element, TreeElements definitions,
       {bool isConst: false, bool checkType: true}) {
     if (!isConst && lazyStatics.contains(element)) {
       return null;
     }
     ConstantExpression value = super.compileVariableWithDefinitions(
@@ skipping 73 matching lines @@
 
   ConstantExpression getConstantForNode(Node node, TreeElements definitions) {
     ConstantExpression constant = nodeConstantMap[node];
     if (constant != null) {
       return constant;
     }
     return definitions.getConstant(node);
   }
 
   ConstantValue getConstantValueForMetadata(MetadataAnnotation metadata) {
-    return getConstantValue(metadata.constant);
+    return getConstantValue(metadataConstantMap[metadata]);
+  }
+
+  ConstantExpression compileMetadata(
+      MetadataAnnotation metadata, Node node, TreeElements elements) {
+    ConstantExpression constant =
+        super.compileMetadata(metadata, node, elements);
+    metadataConstantMap[metadata] = constant;
+    return constant;
   }
 
   void forgetElement(Element element) {
     super.forgetElement(element);
     const ForgetConstantElementVisitor().visit(element, this);
     if (element is AstElement && element.hasNode) {
       element.node.accept(new ForgetConstantNodeVisitor(this));
     }
   }
+
+  @override
+  ConstantValue getConstantValue(ConstantExpression expression) {
+    assert(invariant(CURRENT_ELEMENT_SPANNABLE, expression != null,
+        message: "ConstantExpression is null in getConstantValue."));
+    // TODO(johhniwinther): ensure expressions have been evaluated at this
+    // point. This can't be enabled today due to dartbug.com/26406.
+    if (compiler.serialization.supportsDeserialization) {
+      evaluate(expression);
+    }
+    ConstantValue value = super.getConstantValue(expression);
+    if (value == null &&
+        expression != null &&
+        expression.kind == ConstantExpressionKind.ERRONEOUS) {
+      // TODO(johnniwinther): When the Dart constant system sees a constant
+      // expression as erroneous but the JavaScript constant system finds it ok
+      // we have store a constant value for the erroneous constant expression.
+      // Ensure the computed constant expressions are always the same; that only
+      // the constant values may be different.
+      value = new NullConstantValue();
+    }
+    return value;
+  }
 }
 
 class ForgetConstantElementVisitor
     extends BaseElementVisitor<dynamic, JavaScriptConstantCompiler> {
   const ForgetConstantElementVisitor();
 
   void visitElement(Element e, JavaScriptConstantCompiler constants) {
     for (MetadataAnnotation data in e.implementation.metadata) {
+      constants.metadataConstantMap.remove(data);
       if (data.hasNode) {
         data.node.accept(new ForgetConstantNodeVisitor(constants));
       }
     }
   }
 
   void visitFunctionElement(
       FunctionElement e, JavaScriptConstantCompiler constants) {
     super.visitFunctionElement(e, constants);
     if (e.hasFunctionSignature) {
@@ skipping 14 matching lines @@
     // TODO(ahe): This doesn't belong here. Rename this class and generalize.
     var closureClassMap = constants
         .compiler.closureToClassMapper.closureMappingCache
         .remove(node);
     if (closureClassMap != null) {
       closureClassMap
           .removeMyselfFrom(constants.compiler.enqueuer.codegen.universe);
     }
   }
 }