Fix numeric overflow handling in LayoutRubyBase

Source/core/layout/LayoutRubyBase.cpp

Index: Source/core/layout/LayoutRubyBase.cpp
diff --git a/Source/core/layout/LayoutRubyBase.cpp b/Source/core/layout/LayoutRubyBase.cpp
index 202252e92633744dd7a42db0998d16b19b9811a2..2e2bae4195e2ba49801fb0b13782dac1584fdddf 100644
--- a/Source/core/layout/LayoutRubyBase.cpp
+++ b/Source/core/layout/LayoutRubyBase.cpp
@@ -140,6 +140,10 @@ void LayoutRubyBase::adjustInlineDirectionLineBounds(unsigned expansionOpportuni
     if (maxPreferredLogicalWidth >= logicalWidth)
         return;
 
+    unsigned maxCount = static_cast<unsigned>(LayoutUnit::max().floor());

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

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.

+    if (expansionOpportunityCount > maxCount)
+        expansionOpportunityCount = maxCount;
+
     // Inset the ruby base by half the inter-ideograph expansion amount.
     LayoutUnit inset = (logicalWidth - maxPreferredLogicalWidth) / (expansionOpportunityCount + 1);