Add asserts to ensure that we:

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
===================================================================
--- src/x64/stub-cache-x64.cc	(revision 9277)
+++ src/x64/stub-cache-x64.cc	(working copy)
@@ -645,7 +645,7 @@
                                         scratch1, scratch2, scratch3, name,
                                         miss_label);
 
-    __ EnterInternalFrame();
+    FrameScope scope(masm, StackFrame::INTERNAL);
     // Save the name_ register across the call.
     __ push(name_);
 
@@ -662,7 +662,8 @@
 
     // Restore the name_ register.
     __ pop(name_);
-    __ LeaveInternalFrame();
+
+    // Leave the internal frame.
   }
 
   void LoadWithInterceptor(MacroAssembler* masm,
@@ -670,19 +671,21 @@
                            Register holder,
                            JSObject* holder_obj,
                            Label* interceptor_succeeded) {
-    __ EnterInternalFrame();
-    __ push(holder);  // Save the holder.
-    __ push(name_);  // Save the name.
+    {
+      FrameScope scope(masm, StackFrame::INTERNAL);
+      __ push(holder);  // Save the holder.
+      __ push(name_);  // Save the name.
 
-    CompileCallLoadPropertyWithInterceptor(masm,
-                                           receiver,
-                                           holder,
-                                           name_,
-                                           holder_obj);
+      CompileCallLoadPropertyWithInterceptor(masm,
+                                             receiver,
+                                             holder,
+                                             name_,
+                                             holder_obj);
 
-    __ pop(name_);  // Restore the name.
-    __ pop(receiver);  // Restore the holder.
-    __ LeaveInternalFrame();
+      __ pop(name_);  // Restore the name.
+      __ pop(receiver);  // Restore the holder.
+      // Leave the internal frame.
+    }
 
     __ CompareRoot(rax, Heap::kNoInterceptorResultSentinelRootIndex);
     __ j(not_equal, interceptor_succeeded);
@@ -1139,41 +1142,43 @@
 
     // Save necessary data before invoking an interceptor.
     // Requires a frame to make GC aware of pushed pointers.
-    __ EnterInternalFrame();
+    {
+      FrameScope frame_scope(masm(), StackFrame::INTERNAL);
 
-    if (lookup->type() == CALLBACKS && !receiver.is(holder_reg)) {
-      // CALLBACKS case needs a receiver to be passed into C++ callback.
-      __ push(receiver);
-    }
-    __ push(holder_reg);
-    __ push(name_reg);
+      if (lookup->type() == CALLBACKS && !receiver.is(holder_reg)) {
+        // CALLBACKS case needs a receiver to be passed into C++ callback.
+        __ push(receiver);
+      }
+      __ push(holder_reg);
+      __ push(name_reg);
 
-    // Invoke an interceptor.  Note: map checks from receiver to
-    // interceptor's holder has been compiled before (see a caller
-    // of this method.)
-    CompileCallLoadPropertyWithInterceptor(masm(),
-                                           receiver,
-                                           holder_reg,
-                                           name_reg,
-                                           interceptor_holder);
+      // Invoke an interceptor.  Note: map checks from receiver to
+      // interceptor's holder has been compiled before (see a caller
+      // of this method.)
+      CompileCallLoadPropertyWithInterceptor(masm(),
+                                             receiver,
+                                             holder_reg,
+                                             name_reg,
+                                             interceptor_holder);
 
-    // Check if interceptor provided a value for property.  If it's
-    // the case, return immediately.
-    Label interceptor_failed;
-    __ CompareRoot(rax, Heap::kNoInterceptorResultSentinelRootIndex);
-    __ j(equal, &interceptor_failed);
-    __ LeaveInternalFrame();
-    __ ret(0);
+      // Check if interceptor provided a value for property.  If it's
+      // the case, return immediately.
+      Label interceptor_failed;
+      __ CompareRoot(rax, Heap::kNoInterceptorResultSentinelRootIndex);
+      __ j(equal, &interceptor_failed);
+      frame_scope.GenerateLeaveFrame();
+      __ ret(0);
 
-    __ bind(&interceptor_failed);
-    __ pop(name_reg);
-    __ pop(holder_reg);
-    if (lookup->type() == CALLBACKS && !receiver.is(holder_reg)) {
-      __ pop(receiver);
+      __ bind(&interceptor_failed);
+      __ pop(name_reg);
+      __ pop(holder_reg);
+      if (lookup->type() == CALLBACKS && !receiver.is(holder_reg)) {
+        __ pop(receiver);
+      }
+
+      // Leave the internal frame.
     }
 
-    __ LeaveInternalFrame();
-
     // Check that the maps from interceptor's holder to lookup's holder
     // haven't changed.  And load lookup's holder into |holder| register.
     if (interceptor_holder != lookup->holder()) {