Move the Kernel string offsets into the VM's heap.

runtime/vm/kernel_reader.h

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_KERNEL_READER_H_
 #define RUNTIME_VM_KERNEL_READER_H_
 
 #if !defined(DART_PRECOMPILED_RUNTIME)
 #include <map>
 
@@ skipping 49 matching lines @@
   static void SetupFunctionParameters(TranslationHelper translation_helper_,
                                       DartTypeTranslator type_translator_,
                                       const dart::Class& owner,
                                       const dart::Function& function,
                                       FunctionNode* kernel_function,
                                       bool is_method,
                                       bool is_closure);
 
   void ReadLibrary(Library* kernel_library);
 
-  const dart::String& DartSymbol(String* str) {
-    return translation_helper_.DartSymbol(str);
+  const dart::String& DartSymbol(intptr_t string_index) {
+    return translation_helper_.DartSymbol(string_index);
   }
 
-  uint8_t CharacterAt(String* str, intptr_t index);
+  uint8_t CharacterAt(intptr_t string_index, intptr_t index);
 
  private:
   friend class BuildingTranslationHelper;
 
   void ReadPreliminaryClass(dart::Class* klass, Class* kernel_klass);
   dart::Class& ReadClass(const dart::Library& library,
                          const dart::Class& toplevel_class,
                          Class* kernel_klass);
   void ReadProcedure(const dart::Library& library,
                      const dart::Class& owner,
                      Procedure* procedure,
                      Class* kernel_klass = NULL);
 
   RawArray* MakeFunctionsArray();
 
   // If klass's script is not the script at the uri index, return a PatchClass
   // for klass whose script corresponds to the uri index.
   // Otherwise return klass.
   const Object& ClassForScriptAt(const dart::Class& klass,
                                  intptr_t source_uri_index);
-  Script& ScriptAt(intptr_t source_uri_index, String* import_uri = NULL);
+  Script& ScriptAt(intptr_t source_uri_index, intptr_t import_uri = -1);
 
   void GenerateFieldAccessors(const dart::Class& klass,
                               const dart::Field& field,
                               Field* kernel_field);
 
   void SetupFieldAccessorFunction(const dart::Class& klass,
                                   const dart::Function& function);
 
   dart::Library& LookupLibrary(CanonicalName* library);
   dart::Class& LookupClass(CanonicalName* klass);
@@ skipping 15 matching lines @@
 
   GrowableArray<const dart::Function*> functions_;
   GrowableArray<const dart::Field*> fields_;
 };
 
 }  // namespace kernel
 }  // namespace dart
 
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)
 #endif  // RUNTIME_VM_KERNEL_READER_H_