- Rename class index to class id.

runtime/vm/dart_api_impl.h

Index: runtime/vm/dart_api_impl.h
===================================================================
--- runtime/vm/dart_api_impl.h	(revision 8135)
+++ runtime/vm/dart_api_impl.h	(working copy)
@@ -123,12 +123,12 @@
     return Smi::ValueFromRaw(value);
   }
 
-  static intptr_t ClassIndex(Dart_Handle handle) {
+  static intptr_t ClassId(Dart_Handle handle) {
     RawObject* raw = *(reinterpret_cast<RawObject**>(handle));
     if (!raw->IsHeapObject()) {
       return kSmi;
     }
-    return raw->GetClassIndex();
+    return raw->GetClassId();
   }
 
   // Generates a handle used to designate an error return.