Bug 1433221 - Revert changes to classid checks for object tags; r=bz

As part of applet/java plugin removal in bug 1279218, classid checking
was removed, as it was not obvious that this was used anywhere other
than java plugins. The classid is still a valid attribute on object
tags (and is sometimes used on tags for flash embedding). We want
to use a fallback strategy when we find objects with classid
attributes, as we don't support them, meaning we need to revert our
prior removal of the check.

MozReview-Commit-ID: BKQ34HGTkvt

dom/html/HTMLObjectElement.cpp

@@ -519,7 +519,7 @@ HTMLObjectElement::IntrinsicState() const
 uint32_t
 HTMLObjectElement::GetCapabilities() const
 {
-  return nsObjectLoadingContent::GetCapabilities();
+  return nsObjectLoadingContent::GetCapabilities() | eFallbackIfClassIDPresent;
 }
 
 void