An align attribute should not be applied for wider children

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index 7c0317be2904508c2c8bb47f8f9942dddf60f2b2..6f6266bfd33367ee13b25bcf49b23b4ee8769f61 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -2144,26 +2144,22 @@ void RenderBox::computeMarginsForDirection(MarginDirection flowDirection, const
     }
 
     // CSS 2.1: "If there is exactly one value specified as 'auto', its used value follows from the equality."
-    if (marginEndLength.isAuto() && marginBoxWidth < availableWidth) {
-        marginStart = marginStartWidth;
-        marginEnd = availableWidth - childWidth - marginStart;
-        return;
-    }
-
-    bool adjustFromTextAlign = !marginEndLength.isAuto() && ((!containingBlockStyle->isLeftToRightDirection() && containingBlockStyle->textAlign() == WEBKIT_LEFT)
-        || (containingBlockStyle->isLeftToRightDirection() && containingBlockStyle->textAlign() == WEBKIT_RIGHT));
-    bool hasInvertedDirection = containingBlockStyle->isLeftToRightDirection() != style()->isLeftToRightDirection();
-
-    if ((marginStartLength.isAuto() && marginBoxWidth < availableWidth) || (adjustFromTextAlign && !hasInvertedDirection)) {
-        marginEnd = marginEndWidth;
-        marginStart = availableWidth - childWidth - marginEnd;
-        return;
-    }
+    if (marginBoxWidth < availableWidth) {

[mstensho (USE GERRIT), 2014/12/10 10:45:05]

Should move this check to include center alignment (above) too.

[Kyungtae Kim, 2014/12/10 11:50:38]

Done.

+        bool adjustFromTextAlign = !marginEndLength.isAuto() && ((!containingBlockStyle->isLeftToRightDirection() && containingBlockStyle->textAlign() == WEBKIT_LEFT)
+            || (containingBlockStyle->isLeftToRightDirection() && containingBlockStyle->textAlign() == WEBKIT_RIGHT));
+        bool hasInvertedDirection = containingBlockStyle->isLeftToRightDirection() != style()->isLeftToRightDirection();
+
+        if (marginEndLength.isAuto() || (adjustFromTextAlign && hasInvertedDirection && !marginStartLength.isAuto())) {

[mstensho (USE GERRIT), 2014/12/10 10:45:05]

Now is a good time to get rid of adjustFromTextAlign and hasInvertedDirection,
and just set marginEndLength and/or marginStartLength to Auto when align is
left, center or right.

[Kyungtae Kim, 2014/12/10 11:50:38]

 I think it could be confusing.
Because auto margins always have a priority over align,
we need to check many combinations before setting it.
How do you think about that?

[mstensho (USE GERRIT), 2014/12/10 23:27:00]

The code for WEBKIT_CENTER needs to remain special, because it actually aligns
the margin box, not the border box, in that case. But for WEBKIT_LEFT and
WEBKIT_RIGHT, something like this:

if (containingBlockStyle->textAlign() == WEBKIT_LEFT ||
containingBlockStyle->textAlign() == WEBKIT_RIGHT) {
    enum BlockAlign { None, Start, End };
    BlockAlign blockAlign = None;
    if (containingBlockStyle->textAlign() == WEBKIT_LEFT) {
        if (!containingBlockStyle->isLeftToRightDirection())
            blockAlign = style()->isLeftToRightDirection() ? Start : End;
    } else { // WEBKIT_RIGHT
        if (containingBlockStyle->isLeftToRightDirection())
            blockAlign = !style()->isLeftToRightDirection() ? Start : End;
    }
    if (blockAlign == Start) {
        if (!marginStartLength.isAuto())
            marginEndLength = Length(Auto);
    } else if (blockAlign == End) {
        if (!marginEndLength.isAuto())
            marginStartLength = Length(Auto);
    }
}

And then just handle the auto margins according to the CSS spec, without the
need for any of the two flags.

+            marginStart = marginStartWidth;
+            marginEnd = availableWidth - childWidth - marginStart;
+            return;
+        }
 
-    if (adjustFromTextAlign && hasInvertedDirection) {
-        marginStart = marginStartWidth;
-        marginEnd = availableWidth - childWidth - marginStart;
-        return;
+        if (marginStartLength.isAuto() || adjustFromTextAlign) {
+            marginEnd = marginEndWidth;
+            marginStart = availableWidth - childWidth - marginEnd;
+            return;
+        }
     }
 
     // Either no auto margins, or our margin box width is >= the container width, auto margins will just turn into 0.