Bug 1463605 - Check mMayHaveOpacityAnimation in nsFrame::HasOpacityInternal(). r=birtles

If the mMayHaveOpacityAnimation is false there, we don't need to check opacity
animations at all.

MozReview-Commit-ID: LTYPPXzF8V6

--HG--
extra : rebase_source : ee2c90e04003140944fb4cc255aa3c6f1c07f0b0

layout/generic/nsFrame.cpp

@@ -1553,6 +1553,10 @@ nsIFrame::HasOpacityInternal(float aThreshold,
     return true;
   }
 
+  if (!mMayHaveOpacityAnimation) {
+    return false;
+  }
+
   EffectSet* effects =
     aEffectSet ? aEffectSet : EffectSet::GetEffectSet(this);
   if (!effects) {