Make isolate.h usable without objects-inl.h header.

src/string-builder.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/string-builder.h"
 
+#include "src/isolate-inl.h"
 #include "src/objects-inl.h"
 
 namespace v8 {
 namespace internal {
 
 MaybeHandle<String> ReplacementStringBuilder::ToString() {
   Isolate* isolate = heap_->isolate();
   if (array_builder_.length() == 0) {
     return isolate->factory()->empty_string();
   }
@@ skipping 83 matching lines @@
 
 
 void IncrementalStringBuilder::AppendString(Handle<String> string) {
   ShrinkCurrentPart();
   part_length_ = kInitialPartLength;  // Allocate conservatively.
   Extend();  // Attach current part and allocate new part.
   Accumulate(string);
 }
 }  // namespace internal
 }  // namespace v8