Fix numeric overflow handling in LayoutRubyBase

Fix numeric overflow handling in LayoutRubyBase

Prevent potential divide by zero in LayoutRubyBase by adding an explicit
check for the maximum allowed value, thereby avoiding it to wrap around.

R=wkorman@chromium.org
BUG=518702
TEST=fast/dom/ruby-numeric-overflow.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200282

[eae, 2015-08-11 00:54:44]

Can haz review?

[wkorman, 2015-08-11 01:03:32]

lgtm

https://codereview.chromium.org/1285583004/diff/1/Source/core/layout/LayoutRu...
File Source/core/layout/LayoutRubyBase.cpp (right):

https://codereview.chromium.org/1285583004/diff/1/Source/core/layout/LayoutRu...
Source/core/layout/LayoutRubyBase.cpp:143: unsigned maxCount =
static_cast<unsigned>(LayoutUnit::max().floor());
Do we need to worry about similar overflow here?

https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

Unit tests for this class could be worthwhile at some point to catch this and
similar.

[eae, 2015-08-11 01:09:14]

> Unit tests for this class could be worthwhile at some point to catch this and
> similar.

Agreed.

[eae, 2015-08-11 01:09:17]

The CQ bit was checked by eae@chromium.org

[commit-bot: I haz the power, 2015-08-11 01:09:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1285583004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1285583004/1

[commit-bot: I haz the power, 2015-08-11 01:12:55]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200282