elements.cc CopyDoubleToObjectElements: avoid excessive HandleScopes

BUG=

Review URL: https://codereview.chromium.org/1341763002

Cr-Commit-Position: refs/heads/master@{#30717}

src/elements.cc

@@ -253,14 +253,22 @@ static void CopyDoubleToObjectElements(FixedArrayBase* from_base,
   Isolate* isolate = from_base->GetIsolate();
   Handle<FixedDoubleArray> from(FixedDoubleArray::cast(from_base), isolate);
   Handle<FixedArray> to(FixedArray::cast(to_base), isolate);
-  for (int i = 0; i < copy_size; ++i) {
+
+  // create an outer loop to not waste too much time on creating HandleScopes
+  // on the other hand we might overflow a single handle scope depending on
+  // the copy_size
+  int offset = 0;
+  while (offset < copy_size) {
     HandleScope scope(isolate);
-    if (IsFastSmiElementsKind(to_kind)) {
-      UNIMPLEMENTED();
-    } else {
-      DCHECK(IsFastObjectElementsKind(to_kind));
-      Handle<Object> value = FixedDoubleArray::get(from, i + from_start);
-      to->set(i + to_start, *value, UPDATE_WRITE_BARRIER);
+    offset += 100;
+    for (int i = offset - 100; i < offset && i < copy_size; ++i) {
+      if (IsFastSmiElementsKind(to_kind)) {
+        UNIMPLEMENTED();
+      } else {
+        DCHECK(IsFastObjectElementsKind(to_kind));
+        Handle<Object> value = FixedDoubleArray::get(from, i + from_start);
+        to->set(i + to_start, *value, UPDATE_WRITE_BARRIER);
+      }
     }
   }
 }