Allow multiple dart <script> tags in .sky files

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

Index: sky/engine/core/html/parser/HTMLDocumentParser.h
diff --git a/sky/engine/core/html/parser/HTMLDocumentParser.h b/sky/engine/core/html/parser/HTMLDocumentParser.h
index 23e58ed57e8e9a2eea909793627b3ce1216232b3..b254534d6bfb2a0a8c6f3b3004e12b3697f9cbc9 100644
--- a/sky/engine/core/html/parser/HTMLDocumentParser.h
+++ b/sky/engine/core/html/parser/HTMLDocumentParser.h
@@ -54,7 +54,7 @@ class ScriptSourceCode;
 
 class PumpSession;
 
-class HTMLDocumentParser :  public DocumentParser {
+class HTMLDocumentParser : public DocumentParser, public HTMLScriptRunnerHost {
     WTF_MAKE_FAST_ALLOCATED;
 public:
     static PassRefPtr<HTMLDocumentParser> create(Document& document, bool reportErrors)
@@ -85,6 +85,9 @@ public:
     bool isExecutingScript() const override final;
     void resumeAfterWaitingForImports() override final;
 
+    // From HTMLScriptRunnerHost:
+    void scriptExecutionCompleted();
+
 private:
     HTMLDocumentParser(Document&, bool reportErrors);
 
@@ -116,7 +119,7 @@ private:
     OwnPtr<HTMLParserScheduler> m_parserScheduler;
     TextPosition m_textPosition;
 
-    HTMLScriptRunner m_scriptRunner;
+    OwnPtr<HTMLScriptRunner> m_scriptRunner;
 
     OwnPtr<ParsedChunk> m_lastChunkBeforeScript;
     Deque<OwnPtr<ParsedChunk> > m_pendingChunks;