[CSS Grid Layout] Do not stretch always grid items with auto width

Source/core/layout/LayoutBox.cpp

Index: Source/core/layout/LayoutBox.cpp
diff --git a/Source/core/layout/LayoutBox.cpp b/Source/core/layout/LayoutBox.cpp
index 36c0c273c5b5abb3310c289aa2d71bc9b8a9d42a..614a06899dc0b0d136aaa2234588ffcdecf056ec 100644
--- a/Source/core/layout/LayoutBox.cpp
+++ b/Source/core/layout/LayoutBox.cpp
@@ -1921,7 +1921,7 @@ void LayoutBox::computeLogicalWidth(LogicalExtentComputedValues& computedValues)
     // width.  Use the width from the style context.
     // FIXME: Account for writing-mode in flexible boxes.
     // https://bugs.webkit.org/show_bug.cgi?id=46418
-    if (hasOverrideLogicalContentWidth() && parent()->isFlexibleBoxIncludingDeprecated()) {
+    if (hasOverrideLogicalContentWidth() && (parent()->isFlexibleBoxIncludingDeprecated() || parent()->isLayoutGrid())) {

[Manuel Rego, 2015/07/13 12:40:07]

This if here worries me as the code to manage "min-width: auto"; is a few lines
below.

Actually I've been checking a few cases that are breaking "min-width: auto;"
behavior:
* http://jsbin.com/rowabah/1/edit?html,css,output
* http://jsbin.com/mawovey/1/edit?html,css,output 

         computedValues.m_extent = overrideLogicalContentWidth() + borderAndPaddingLogicalWidth();
         return;
     }