Change compositing/gestures tests to avoid a one pixel difference

LayoutTests/compositing/gestures/resources/link-highlight-style.css

 /*Used for applying style to a <span> so it looks like a highlight*/
 .fauxHighlight {
   -webkit-border-radius: 3px;
   background-color: rgb(0, 255, 0);
   color: rgb(0, 255, 0);
 }
 
 .fauxHighlightSquare {
   background-color: rgb(0, 255, 0);
   color: rgb(0, 255, 0);
 }
 
 .opaqueHighlight {
   -webkit-tap-highlight-color: rgb(0, 255, 0);
 }
 
 .transparentHighlight {
   -webkit-tap-highlight-color: rgba(0, 255, 0, 0.5);
 }
 
 .activeLink {
   color: rgb(0, 255, 0);
 }
 
+a {
+  text-decoration: none;
+}
+
 a:active {
   color: rgb(0, 255, 0);
 }
 
 a.needsFix:active {
   color: rgb(255, 255, 255);
 }
 
 /*Used for a floating DIV simulating a highlight*/
 .highlightDiv {
   -webkit-border-radius: 3px;
   background-color: rgb(0, 255, 0);
   z-index: 1;
   position: absolute;
 }
 
 .squaredHighlight {
   -webkit-border-radius: 0px;
 }
 
 .composited {
   -webkit-transform: translateZ(0);
 }