Reland 8636: Implement setting the length property for FixedDoubleArrays.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index e069b7994eb90cac0e86e5a75790f464f2275ac9..5726b3739320e30c7eeb0eb23dd87c31c760b933 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -4007,7 +4007,8 @@ bool JSObject::HasIndexedInterceptor() {
 
 
 bool JSObject::AllowsSetElementsLength() {
-  bool result = elements()->IsFixedArray();
+  bool result = elements()->IsFixedArray() ||
+      elements()->IsFixedDoubleArray();
   ASSERT(result == !HasExternalArrayElements());
   return result;
 }