Add TypeVariable object on runtime to support reflection on type variables.

sdk/lib/_internal/compiler/implementation/js_backend/backend.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart b/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
index 754e5aa0bad1b1481b6868da298300901da924c3..ee1589190d8b71d21efe615b911b2be1ef9c3d5c 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/backend.dart
@@ -406,6 +406,8 @@ class JavaScriptBackend extends Backend {
           checkedModeHelpers,
           key: (helper) => helper.name.slowToString());
 
+  TypeVariableConstantHandler typeVarHandler;

[ahe, 2013/10/14 13:07:07]

Rename to typeVariableHandler (please don't abbreviate).

[zarah, 2013/10/15 14:20:02]

Done.

+
   /// Number of methods compiled before considering reflection.
   int preMirrorsMethodCount = 0;
 
@@ -420,6 +422,7 @@ class JavaScriptBackend extends Backend {
     builder = new SsaBuilderTask(this);
     optimizer = new SsaOptimizerTask(this);
     generator = new SsaCodeGeneratorTask(this);
+    typeVarHandler = new TypeVariableConstantHandler(this);
   }
 
   static Namer determineNamer(Compiler compiler) {
@@ -663,6 +666,8 @@ class JavaScriptBackend extends Backend {
         new TypeMask.nonNullExact(jsFixedArrayClass));
     extendableArrayType = new HBoundedType(
         new TypeMask.nonNullExact(jsExtendableArrayClass));
+
+    typeVarHandler.initializeHelperClass();

[ahe, 2013/10/14 13:07:07]

I think I would prefer if the helper class was initialized here. This makes it
easier to find helper classes.

[zarah, 2013/10/15 14:20:02]

Done.

   }
 
   void validateInterceptorImplementsAllObjectMethods(
@@ -790,6 +795,10 @@ class JavaScriptBackend extends Backend {
   void registerInstantiatedClass(ClassElement cls,
                                  Enqueuer enqueuer,
                                  TreeElements elements) {
+    if (!cls.typeVariables.isEmpty) {
+      typeVarHandler.registerClassWithTypeVars(cls);
+    }
+
     if (!seenAnyClass) {
       seenAnyClass = true;
       if (enqueuer.isResolutionQueue) {
@@ -1806,6 +1815,14 @@ class JavaScriptBackend extends Backend {
       }
       metadataConstants.clear();
     }
+
+    if (isTreeShakingDisabled) {
+      if (enqueuer.isResolutionQueue) {
+        typeVarHandler.onResolutionQueueEmpty(enqueuer);
+      } else {
+        typeVarHandler.onCodegenQueueEmpty();
+      }
+    }
   }
 }