Lower priority of async scripts

Source/core/fetch/FetchRequest.h

Index: Source/core/fetch/FetchRequest.h
diff --git a/Source/core/fetch/FetchRequest.h b/Source/core/fetch/FetchRequest.h
index 7117fc92e04adb0b012573071d77bb7cb843d685..2d12e458838867c8f917025c6df9de82b45796f2 100644
--- a/Source/core/fetch/FetchRequest.h
+++ b/Source/core/fetch/FetchRequest.h
@@ -56,6 +56,8 @@ public:
     ResourceLoadPriority priority() const { return m_priority; }
     bool forPreload() const { return m_forPreload; }
     void setForPreload(bool forPreload) { m_forPreload = forPreload; }
+    bool execAsync() const { return m_execAsync; }
+    void setExecAsync(bool execAsync) { m_execAsync = execAsync; }
     DeferOption defer() const { return m_defer; }
     void setDefer(DeferOption defer) { m_defer = defer; }
     void setContentSecurityCheck(ContentSecurityPolicyCheck contentSecurityPolicyOption) { m_options.contentSecurityPolicyOption = contentSecurityPolicyOption; }
@@ -71,6 +73,7 @@ private:
     ResourceLoaderOptions m_options;
     ResourceLoadPriority m_priority;
     bool m_forPreload;
+    bool m_execAsync;

[eseidel, 2014/09/03 15:15:38]

Strange that this is different from DeferOption.

[Pat Meenan, 2014/09/03 16:16:17]

Looks like DeferOption is specific to images right now (if Chrome decides it
shouldn't load the image) and it completely blocks the fetch:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

I could expand the enum to include an indicator that it should still be loaded
but asynchronously which would eliminate the parallel execAsync plumbing.  I'm a
bit concerned that it might be confusing though since the current use of
DeferOption is to actually prevent the fetches.

     DeferOption m_defer;
     OriginRestriction m_originRestriction;
 };