Create frequently used symbols in the vm isolate

vm/isolate.h

Index: vm/isolate.h
===================================================================
--- vm/isolate.h	(revision 9729)
+++ vm/isolate.h	(working copy)
@@ -33,6 +33,7 @@
 class RawError;
 class StackResource;
 class StubCode;
+class Symbols;
 class Zone;
 
 class Isolate : public BaseIsolate {
@@ -181,6 +182,17 @@
 
   Debugger* debugger() const { return debugger_; }
 
+  GcPrologueCallbacks& gc_prologue_callbacks() {
+    return gc_prologue_callbacks_;
+  }
+
+  GcEpilogueCallbacks& gc_epilogue_callbacks() {
+    return gc_epilogue_callbacks_;
+  }
+
+  Symbols* symbols() const { return symbols_; }
+  void set_symbols(Symbols* value) { symbols_ = value; }
+
   static void SetCreateCallback(Dart_IsolateCreateCallback cb) {
     create_callback_ = cb;
   }
@@ -202,14 +214,6 @@
     return shutdown_callback_;
   }
 
-  GcPrologueCallbacks& gc_prologue_callbacks() {
-    return gc_prologue_callbacks_;
-  }
-
-  GcEpilogueCallbacks& gc_epilogue_callbacks() {
-    return gc_epilogue_callbacks_;
-  }
-
  private:
   Isolate();
 
@@ -249,6 +253,7 @@
   uword spawn_data_;
   GcPrologueCallbacks gc_prologue_callbacks_;
   GcEpilogueCallbacks gc_epilogue_callbacks_;
+  Symbols* symbols_;
 
   static Dart_IsolateCreateCallback create_callback_;
   static Dart_IsolateInterruptCallback interrupt_callback_;