Bug 1389421 - Support nonce IDL property; r=ckerschb,smaug

We already support the actual functionality, but nobody added support
for the IDL property to the .webidl file.

Also added <style nonce> to the web-platform-tests reflection tests,
since nobody updated that to the current spec either.

This does not add support for .nonce to SVGScriptElement, because I
couldn't find any standard that specified it.  I updated the wpt tests
to expect .nonce to work on HTMLScriptElement but not SVGScriptElement.

MozReview-Commit-ID: F1K7WMfMoDi

dom/html/HTMLScriptElement.h

@@ -81,6 +81,14 @@ public:
   {
     SetOrRemoveNullableStringAttr(nsGkAtoms::crossorigin, aCrossOrigin, aError);
   }
+  void GetNonce(nsAString& aNonce) const
+  {
+    GetHTMLAttr(nsGkAtoms::nonce, aNonce);
+  }
+  void SetNonce(const nsAString& aNonce, ErrorResult& aRv)
+  {
+    SetHTMLAttr(nsGkAtoms::nonce, aNonce, aRv);
+  }
   void GetIntegrity(nsAString& aIntegrity)
   {
     GetHTMLAttr(nsGkAtoms::integrity, aIntegrity);