import changes from tenfourfox:

bug1444231, bug1450688, bug1464784, bug1458048, bug1316649
- #491: new fix for M1452416 (8ebe4e8e5) (ported)
- #508: unprefix -moz-columns (M1300895 plus additional work) (b9bdadfef)

layout/generic/nsHTMLReflowState.cpp

@@ -441,6 +441,11 @@ void nsHTMLReflowState::InitCBReflowState()
     mCBReflowState = nullptr;
     return;
   }
+  if (parentReflowState->mFlags.mDummyParentReflowState) {
+    // from bug 1316649
+    mCBReflowState = parentReflowState;
+    return;
+  }
 
   if (parentReflowState->frame == frame->GetContainingBlock()) {
     // Inner table frames need to use the containing block of the outer