Bug 824862: Don't skip over generated-content children of a flex container, even if they look like whitespace. r=bz

layout/base/nsCSSFrameConstructor.cpp

@@ -9532,7 +9532,15 @@ nsCSSFrameConstructor::CreateNeededAnonFlexItems(
     // there's anything wrappable immediately after it. If not, we just drop
     // the whitespace and move on. (We're not supposed to create any anonymous
     // flex items that _only_ contain whitespace).
-    if (iter.item().IsWhitespace(aState)) {
+    // (BUT if this is generated content, then we don't give whitespace nodes
+    // any special treatment, because they're probably not really whitespace --
+    // they're just temporarily empty, waiting for their generated text.)
+    // XXXdholbert If this node's generated text will *actually end up being
+    // entirely whitespace*, then we technically should still skip over it, per
+    // the flexbox spec. I'm not bothering with that at this point, since it's
+    // a pretty extreme edge case.
+    if (!aParentFrame->IsGeneratedContentFrame() &&
+        iter.item().IsWhitespace(aState)) {
       FCItemIterator afterWhitespaceIter(iter);
       bool hitEnd = afterWhitespaceIter.SkipWhitespace(aState);
       bool nextChildNeedsAnonFlexItem =