Bug 812687 part 6: Rename & invert polarity of a flexbox frame-state-bit, for consistency with grid. r=mats

This patch is just flipping some logic in a way that should produce the same
outcome, so it shouldn't affect behavior.

MozReview-Commit-ID: LM4HbJD3D9w

layout/generic/nsFlexContainerFrame.cpp

@@ -2263,9 +2263,9 @@ nsFlexContainerFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 
   typedef CSSOrderAwareFrameIterator::OrderState OrderState;
   OrderState orderState =
-    HasAnyStateBits(NS_STATE_FLEX_CHILDREN_REORDERED)
-    ? OrderState::eKnownUnordered
-    : OrderState::eKnownOrdered;
+    HasAnyStateBits(NS_STATE_FLEX_NORMAL_FLOW_CHILDREN_IN_CSS_ORDER)
+    ? OrderState::eKnownOrdered
+    : OrderState::eKnownUnordered;
 
   CSSOrderAwareFrameIterator iter(this, kPrincipalList,
                                   CSSOrderAwareFrameIterator::eIncludeAll,
@@ -3581,9 +3581,9 @@ nsFlexContainerFrame::GenerateFlexLines(
                                   OrderingPropertyForIter(this));
 
   if (iter.ItemsAreAlreadyInOrder()) {
-    RemoveStateBits(NS_STATE_FLEX_CHILDREN_REORDERED);
+    AddStateBits(NS_STATE_FLEX_NORMAL_FLOW_CHILDREN_IN_CSS_ORDER);
   } else {
-    AddStateBits(NS_STATE_FLEX_CHILDREN_REORDERED);
+    RemoveStateBits(NS_STATE_FLEX_NORMAL_FLOW_CHILDREN_IN_CSS_ORDER);
   }
 
   for (; !iter.AtEnd(); iter.Next()) {

layout/generic/nsFrameStateBits.h

@@ -310,9 +310,9 @@ FRAME_STATE_BIT(Box, 61, NS_FRAME_MOUSE_THROUGH_NEVER)
 
 FRAME_STATE_GROUP(FlexContainer, nsFlexContainerFrame)
 
-// Set for a flex container whose children have been reordered due to 'order'.
-// (Means that we have to be more thorough about checking them for sortedness.)
-FRAME_STATE_BIT(FlexContainer, 20, NS_STATE_FLEX_CHILDREN_REORDERED)
+// True iff the normal flow children are already in CSS 'order' in the
+// order they occur in the child frame list.
+FRAME_STATE_BIT(FlexContainer, 20, NS_STATE_FLEX_NORMAL_FLOW_CHILDREN_IN_CSS_ORDER)
 
 // Set for a flex container that is emulating a legacy
 // 'display:-webkit-{inline-}box' container.