b=454085 Add text-indent:0 in mtable to prevent unexpected spaces r+sr=roc

layout/mathml/content/src/mathml.css

@@ -226,6 +226,7 @@ mtable {
   display: inline-table;
   border-collapse: separate;
   border-spacing: 0;
+  text-indent: 0;
 }
 mtable[frame="none"] {
   border: none;