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

src/runtime/runtime-strings.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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/conversions-inl.h"
+#include "src/isolate-inl.h"
 #include "src/regexp/jsregexp-inl.h"
 #include "src/regexp/jsregexp.h"
 #include "src/string-builder.h"
 #include "src/string-search.h"
 
 namespace v8 {
 namespace internal {
 
 
 // Perform string match of pattern on subject, starting at start index.
@@ skipping 1309 matching lines @@
 
 
 RUNTIME_FUNCTION(Runtime_StringGetLength) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
   return Smi::FromInt(s->length());
 }
 }  // namespace internal
 }  // namespace v8