[css-flexbox] Fix main size calculation for overflow:auto

third_party/WebKit/LayoutTests/css3/flexbox/overflow-auto-resizes-correctly.html

Index: third_party/WebKit/LayoutTests/css3/flexbox/overflow-auto-resizes-correctly.html
diff --git a/third_party/WebKit/LayoutTests/css3/flexbox/overflow-auto-resizes-correctly.html b/third_party/WebKit/LayoutTests/css3/flexbox/overflow-auto-resizes-correctly.html
index b7cf506354bcb6ddcbdde3fe5e43368d5cb23e6c..7370ca40bdec42b6b3e5616347089f1ec3a81c2d 100644
--- a/third_party/WebKit/LayoutTests/css3/flexbox/overflow-auto-resizes-correctly.html
+++ b/third_party/WebKit/LayoutTests/css3/flexbox/overflow-auto-resizes-correctly.html
@@ -9,7 +9,7 @@
 }
 .hflex {
   display: flex;
-  flex-direction: box;
+  flex-direction: row;
   max-height: 200px;
   margin: 10px 0 10px 0;
 }
@@ -51,6 +51,12 @@
   </div>
 </div>
 
+<div style="display: flex; width: 100px; height: 100px;">
+  <div id="inner" style="flex: none; height: 100px; overflow: auto;">
+    <div style="width: 100px; height: 150px; background-color: green;"></div>
+  </div>
+</div>
+
 <!-- This div is only for measuring scrollbar size -->
 <div id="measure" style="height: 100px; width: 100px; display: inline-box; overflow: auto;">
   <div style="min-height: 300px;"></div>
@@ -69,6 +75,10 @@
   var scrollbarSize = measure.offsetWidth - measure.clientWidth;
   shouldNotBe("scrollbarSize", "0");
 
+  var inner = document.getElementById('inner');
+  shouldBe("inner.clientWidth", "100");
+  shouldBe("inner.offsetWidth", "100 + scrollbarSize");
+
   var vbox = document.querySelector('.vbox');
   shouldBe("vbox.clientWidth", "100 - scrollbarSize");
 </script>