Add Settings::useDefaultImageInterpolationQuality and use it in repaint tests

third_party/WebKit/LayoutTests/fast/repaint/resources/text-based-repaint.js

 // Asynchronous tests should manually call finishRepaintTest at the appropriate
 // time.
 window.testIsAsync = false;
 window.outputRepaintRects = true;
 window.generateMinimumRepaint = false; // See comments about 'Minimum repaint' below.
 
 // All repaint tests are asynchronous.
 if (window.testRunner)
     testRunner.waitUntilDone();
 
+if (window.internals)

[pdr., 2016/06/08 18:40:01]

Do we need to reset this at the end of the test?

[Xianzhu, 2016/06/08 18:41:24]

Layout test runner will reset all settings after running a test.

+    internals.settings.setUseDefaultImageInterpolationQuality(true);
+
 function runRepaintTest()
 {
     if (!window.testRunner || !window.internals) {
         setTimeout(repaintTest, 500);
         return;
     }
 
     if (window.enablePixelTesting)
         testRunner.dumpAsTextWithPixelResults();
     else
@@ skipping 160 matching lines @@
             } else {
                 var newRect = [xBegin, y, xWidth, 1];
                 nextRectsMayContinue.push(newRect);
                 result.push(newRect);
             }
         }
         rectsMayContinue = nextRectsMayContinue;
     }
     return result;
 }