Port revision 6934 and 6993 (plus fix from 6935) to the 3.0 branch.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index ff2718eba87b29e38d73af440dc26e2d480dfd49..c4a305a14283f80b2172855be58fa36253b669bf 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -769,6 +769,10 @@ bool Object::HasSpecificClassOf(String* name) {
 
 
 MaybeObject* Object::GetElement(uint32_t index) {
+  // GetElement can trigger a getter which can cause allocation.
+  // This was not always the case. This ASSERT is here to catch
+  // leftover incorrect uses.
+  ASSERT(Heap::IsAllocationAllowed());
   return GetElementWithReceiver(this, index);
 }