Compute frontend/backend specific constants.

sdk/lib/_internal/compiler/implementation/js_emitter/container_builder.dart

Index: sdk/lib/_internal/compiler/implementation/js_emitter/container_builder.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_emitter/container_builder.dart b/sdk/lib/_internal/compiler/implementation/js_emitter/container_builder.dart
index eeb19bef119e6fa8d1ae14461570a71f2fc863ea..7f1cf891f5dc72f952b488dc05b7c68852e04e89 100644
--- a/sdk/lib/_internal/compiler/implementation/js_emitter/container_builder.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_emitter/container_builder.dart
@@ -43,7 +43,7 @@ class ContainerBuilder extends CodeEmitterHelper {
       // directly.
       return;
     }
-    ConstantHandler handler = compiler.constantHandler;
+    JavaScriptBackendConstantHandler handler = backend.constantHandler;
     List<String> names = selector.getOrderedNamedArguments();
 
     String invocationName = namer.invocationName(selector);
@@ -99,7 +99,7 @@ class ContainerBuilder extends CodeEmitterHelper {
           parametersBuffer[optionalParameterStart + index] =
               new jsAst.Parameter(jsName);
         } else {
-          Constant value = handler.initialVariableValues[element];
+          Constant value = handler.getConstantForVariable(element);
           if (value == null) {
             argumentsBuffer[count] = task.constantReference(new NullConstant());
           } else {
@@ -505,9 +505,11 @@ class ContainerBuilder extends CodeEmitterHelper {
         if (backend.mustRetainMetadata) {
           List<MetadataAnnotation> annotations = parameter.metadata.toList();
           Iterable<int> metadataIndices =
-              annotations.map((MetadataAnnotation a) {
-            compiler.constantHandler.addCompileTimeConstantForEmission(a.value);
-            return task.metadataEmitter.reifyMetadata(a);
+              annotations.map((MetadataAnnotation annotation) {
+            Constant constant =
+                backend.constantHandler.getConstantForMetadata(annotation);
+            backend.constantHandler.addCompileTimeConstantForEmission(constant);
+            return task.metadataEmitter.reifyMetadata(annotation);
           });
           expressions.add(metadataIndices.isNotEmpty ? metadataIndices.toList()
                                                      : js('[]'));