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

pkg/compiler/lib/src/compile_time_constants.dart

Index: pkg/compiler/lib/src/compile_time_constants.dart
diff --git a/pkg/compiler/lib/src/compile_time_constants.dart b/pkg/compiler/lib/src/compile_time_constants.dart
index 71962e88957bcc163fdc0d7df455753022b6ab8c..bbabcf9f9aaf521a67cad7c5d96b3117f4471026 100644
--- a/pkg/compiler/lib/src/compile_time_constants.dart
+++ b/pkg/compiler/lib/src/compile_time_constants.dart
@@ -165,9 +165,7 @@ abstract class ConstantCompilerBase implements ConstantCompiler {
   @override
   @deprecated
   ConstantValue getConstantValueForVariable(VariableElement element) {
-    ConstantExpression constant = initialVariableValues[element.declaration];
-    // TODO(johnniwinther): Support eager evaluation of the constant.
-    return constant != null ? getConstantValue(constant) : null;
+    return getConstantValue(initialVariableValues[element.declaration]);
   }
 
   ConstantExpression compileConstant(VariableElement element) {
@@ -322,27 +320,8 @@ abstract class ConstantCompilerBase implements ConstantCompiler {
     return constantValueMap.containsKey(expression);
   }
 
-  @override
   ConstantValue getConstantValue(ConstantExpression expression) {
-    assert(invariant(CURRENT_ELEMENT_SPANNABLE, expression != null,
-        message: "ConstantExpression is null in getConstantValue."));
-    // TODO(johnniwinther): 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 = constantValueMap[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;
+    return constantValueMap[expression];
   }
 
   ConstantExpression compileNode(Node node, TreeElements elements,
@@ -380,7 +359,7 @@ class DartConstantCompiler extends ConstantCompilerBase {
       Node node, TreeElements definitions,
       {bool isConst: true}) {
     ConstantExpression constant = definitions.getConstant(node);
-    if (constant != null && hasConstantValue(constant)) {
+    if (constant != null && getConstantValue(constant) != null) {
       return constant;
     }
     constant =