Allow multiple dart <script> tags in .sky files

sky/engine/core/html/parser/HTMLScriptRunner.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SKY_ENGINE_CORE_HTML_PARSER_HTMLSCRIPTRUNNER_H_
 #define SKY_ENGINE_CORE_HTML_PARSER_HTMLSCRIPTRUNNER_H_
 
+#include "base/memory/weak_ptr.h"
+#include "sky/engine/core/app/AbstractModule.h"
 #include "sky/engine/core/html/HTMLElement.h"
 #include "sky/engine/wtf/Vector.h"
 #include "sky/engine/wtf/text/TextPosition.h"
 
 namespace blink {
 
+class HTMLScriptRunnerHost {
+ public:
+  virtual void scriptExecutionCompleted() = 0;
+};
+
+// Dart script blocks can include 'import' statements which can introduce
+// additional dependencies which need to be resolved before the script can
+// be executed.  The job of this class is to insulate the rest of the system
+// from this complexity and take in a script and always produce a callback
+// to continue parsing when that script completes/errors out, etc.
+
 class HTMLScriptRunner {
 public:
-    HTMLScriptRunner();
+ static PassOwnPtr<HTMLScriptRunner> createForScript(
+     PassRefPtr<HTMLScriptElement>,
+     TextPosition,
+     HTMLScriptRunnerHost*);
     ~HTMLScriptRunner();
 
-    bool isExecutingScript() const { return m_isExecutingScript; }
+    void start();
 
-    void runScript(PassRefPtr<HTMLScriptElement>, TextPosition);
+    bool isExecutingScript() const;
 
 private:
-    void executeScript(PassRefPtr<HTMLScriptElement>, TextPosition);
+ HTMLScriptRunner(PassRefPtr<HTMLScriptElement>,
+                  TextPosition,
+                  HTMLScriptRunnerHost*);
 
-    bool m_isExecutingScript;
-    TextPosition m_textPosition;
+ enum State {
+   StateInitial,    // No script.
+   StateLoading,    // Waiting on imports to load.
+   StateExecuting,  // Actually running the script.
+   StateCompleted,  // Done, always hit this state regardless of success.
+ };
+
+ enum AdvanceType {
+   ExecutionNormal,
+   ExecutionFailure,
+ };
+
+ // Advancing to StateCompleted may cause the host to delete us.
+ void advanceTo(State, AdvanceType = ExecutionNormal);
+
+ void executeLibrary(RefPtr<AbstractModule> module, RefPtr<DartValue> library);
+ void scriptFailed();
+
+ HTMLScriptRunnerHost* m_host;
+ RefPtr<HTMLScriptElement> m_element;
+ TextPosition m_position;
+ State m_state;
+ base::WeakPtrFactory<HTMLScriptRunner> m_weakFactory;
 };
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_HTML_PARSER_HTMLSCRIPTRUNNER_H_