Marquee width should not change a fixed width of its container.

Source/core/html/HTMLMarqueeElement.cpp

Index: Source/core/html/HTMLMarqueeElement.cpp
diff --git a/Source/core/html/HTMLMarqueeElement.cpp b/Source/core/html/HTMLMarqueeElement.cpp
index a0d7155fc2dae621d930e2f32d0627de46b9b135..418e088f0c2afa2a1803d1df274df4774e168b90 100644
--- a/Source/core/html/HTMLMarqueeElement.cpp
+++ b/Source/core/html/HTMLMarqueeElement.cpp
@@ -71,4 +71,10 @@ void HTMLMarqueeElement::removedFrom(ContainerNode* insertionPoint)
     }
 }
 
+bool HTMLMarqueeElement::isHorizontal() const
+{
+    AtomicString direction = getAttribute(HTMLNames::directionAttr);
+    return direction != "down" && direction != "up";

[mstensho (USE GERRIT), 2015/06/24 08:24:37]

I suddenly started to wonder about the case-sensitive matches here, but I see
that this is in line with the rest of the implementation. <marquee
direction="DoWN"> does indeed become horiontal (while <marquee direction="down">
becomes vertical). Nothing to worry about, then. Weird, though.

[changseok, 2015/06/25 06:41:34]

I think that's a parser issue. Parser presumably ignores the unmatched string so
that we just see the default direction, horizontal left. Blink parser seems
stricter than the others. Gecko, webkit are not case sensitive, but blink is.
Do you think we need to ignore cases here?

[mstensho (USE GERRIT), 2015/06/25 07:46:46]

It's weird to be case-sensitive in this case, but your code here is fine. If we
want to fix this, we should do it in a separate CL.

+}
+
 } // namespace blink