Merge CoreTypes and CoreClasses into CommonElements.

pkg/compiler/lib/src/types/masks.dart

Index: pkg/compiler/lib/src/types/masks.dart
diff --git a/pkg/compiler/lib/src/types/masks.dart b/pkg/compiler/lib/src/types/masks.dart
index f44446ab6abc0717b1b944538bdab7b4affca667..a713dc8acb4ac2e5c7825578c79b6ed385b2f72b 100644
--- a/pkg/compiler/lib/src/types/masks.dart
+++ b/pkg/compiler/lib/src/types/masks.dart
@@ -69,11 +69,11 @@ class CommonMasks {
   TypeMask _unmodifiableArrayType;
   TypeMask _interceptorType;
 
-  TypeMask get dynamicType => _dynamicType ??=
-      new TypeMask.subclass(closedWorld.coreClasses.objectClass, closedWorld);
+  TypeMask get dynamicType => _dynamicType ??= new TypeMask.subclass(
+      closedWorld.commonElements.objectClass, closedWorld);
 
   TypeMask get nonNullType => _nonNullType ??= new TypeMask.nonNullSubclass(
-      closedWorld.coreClasses.objectClass, closedWorld);
+      closedWorld.commonElements.objectClass, closedWorld);
 
   TypeMask get intType => _intType ??= new TypeMask.nonNullSubclass(
       backendClasses.intImplementation, closedWorld);