Revert "Add ClassMirror.isAbstract to the API and VM implementation."

sdk/lib/_internal/lib/js_mirrors.dart

Index: sdk/lib/_internal/lib/js_mirrors.dart
diff --git a/sdk/lib/_internal/lib/js_mirrors.dart b/sdk/lib/_internal/lib/js_mirrors.dart
index 089f61f786e505a278a69363ebe662b6957523ea..18829bf7038177cfd16067e19184be43f43138a3 100644
--- a/sdk/lib/_internal/lib/js_mirrors.dart
+++ b/sdk/lib/_internal/lib/js_mirrors.dart
@@ -1146,8 +1146,6 @@ class JsTypeBoundClassMirror extends JsDeclarationMirror
 
   bool get isTopLevel => _class.isTopLevel;
 
-  bool get isAbstract => _class.isAbstract;
-
   SourceLocation get location => _class.location;
 
   MirrorSystem get mirrors => _class.mirrors;
@@ -1565,8 +1563,6 @@ class JsClassMirror extends JsTypeMirror with JsObjectMirror
 
   // TODO(ahe): Implement this.
   Function operator [](Symbol name) => throw new UnimplementedError();
-
-  bool get isAbstract => throw new UnimplementedError();
 }
 
 class JsVariableMirror extends JsDeclarationMirror implements VariableMirror {
@@ -2074,8 +2070,6 @@ class JsFunctionTypeMirror extends BrokenClassMirror
   get _namedArguments => JS('=Object', '#.named', _typeData);
   bool get isOriginalDeclaration => true;
 
-  bool get isAbstract => false;
-
   TypeMirror get returnType {
     if (_cachedReturnType != null) return _cachedReturnType;
     if (_isVoid) return _cachedReturnType = JsMirrorSystem._voidType;