Set global proxy internal field count based on the global object template.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 9e3c0372ce2e34c091dcda0510015f217c09b823..d07c93d355926160d28ed3b805b7c040cd54e87c 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -8504,6 +8504,10 @@ class JSGlobalProxy : public JSObject {
 
   inline bool IsDetachedFrom(JSGlobalObject* global) const;
 
+  static int SizeFor(int internal_field_count) {

[jochen (gone - plz use gerrit), 2016/11/04 08:06:23]

can you move the body of this method to objects-inl.h please

Also add a DCHECK that internal_field_count is non-negative.

Maybe SizeWithInternalFields() or so would be a better name?

[dcheng, 2016/11/04 09:27:19]

Done.

+    return kHeaderSize + internal_field_count * kPointerSize;
+  }
+
   // Dispatched behavior.
   DECLARE_PRINTER(JSGlobalProxy)
   DECLARE_VERIFIER(JSGlobalProxy)
@@ -8511,9 +8515,7 @@ class JSGlobalProxy : public JSObject {
   // Layout description.
   static const int kNativeContextOffset = JSObject::kHeaderSize;
   static const int kHashOffset = kNativeContextOffset + kPointerSize;
-  static const int kSize = kHashOffset + kPointerSize;

[jochen (gone - plz use gerrit), 2016/11/04 08:06:23]

kHeaderSize would usually not contain any of the data, so I think we should
stick with kSize here

[dcheng, 2016/11/04 09:27:19]

Done.

-  static const int kSizeWithInternalFields =
-      kSize + v8::Context::kProxyInternalFieldCount * kPointerSize;
+  static const int kHeaderSize = kHashOffset + kPointerSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSGlobalProxy);