Merge 120934 - Non-fixed length margins don't work with align=center

Source/WebCore/rendering/RenderBox.cpp

Index: Source/WebCore/rendering/RenderBox.cpp
===================================================================
--- Source/WebCore/rendering/RenderBox.cpp	(revision 121273)
+++ Source/WebCore/rendering/RenderBox.cpp	(working copy)
@@ -1833,8 +1833,8 @@
     if ((marginStartLength.isAuto() && marginEndLength.isAuto() && childWidth < containerWidth)
         || (!marginStartLength.isAuto() && !marginEndLength.isAuto() && containingBlock->style()->textAlign() == WEBKIT_CENTER)) {
         // Other browsers center the margin box for align=center elements so we match them here.
-        LayoutUnit marginStartWidth = marginStartLength.value();
-        LayoutUnit marginEndWidth = marginEndLength.value();
+        LayoutUnit marginStartWidth = minimumValueForLength(marginStartLength, containerWidth, renderView);
+        LayoutUnit marginEndWidth = minimumValueForLength(marginEndLength, containerWidth, renderView);
         LayoutUnit centeredMarginBoxStart = max<LayoutUnit>(0, (containerWidth - childWidth - marginStartWidth - marginEndWidth) / 2);
         containingBlock->setMarginStartForChild(this, centeredMarginBoxStart + marginStartWidth);
         containingBlock->setMarginEndForChild(this, containerWidth - childWidth - containingBlock->marginStartForChild(this) + marginEndWidth);