Resolve inline margins in over-constrained situations correctly.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index 6f2ceee06cd38b7eebf8828ca9cde565f9b1a570..ac5e04998211f42304e18a49b431a2ed900d3830 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -2708,14 +2708,17 @@ void LayoutBox::ComputeLogicalWidth(
            computed_values.margins_.end_) &&
       !IsFloating() && !IsInline() && !cb->IsFlexibleBoxIncludingDeprecated() &&
       !cb->IsLayoutGrid()) {
-    LayoutUnit new_margin = container_logical_width - computed_values.extent_ -
-                            cb->MarginStartForChild(*this);
+    LayoutUnit new_margin_total =
+        container_logical_width - computed_values.extent_;
     bool has_inverted_direction = cb->Style()->IsLeftToRightDirection() !=
                                   Style()->IsLeftToRightDirection();
-    if (has_inverted_direction)
-      computed_values.margins_.start_ = new_margin;
-    else
-      computed_values.margins_.end_ = new_margin;
+    if (has_inverted_direction) {
+      computed_values.margins_.start_ =
+          new_margin_total - computed_values.margins_.end_;
+    } else {
+      computed_values.margins_.end_ =
+          new_margin_total - computed_values.margins_.start_;
+    }
   }
 
   if (style_to_use.TextAutosizingMultiplier() != 1 &&