Add debug output to see what happens during win10 printing

third_party/WebKit/LayoutTests/printing/resources/webgl-repeated-printing-common.js

 var gl;
 
 function main()
 {
   if (!window.testRunner) {
     testFailed("Requires window.testRunner");
   } else {
     testRunner.waitUntilDone();
     testRunner.setPrinting();
     testRunner.dumpAsText();
@@ skipping 48 matching lines @@
   pixel = [
     data[4 * (width * y + x) + 0],
     data[4 * (width * y + x) + 1],
     data[4 * (width * y + x) + 2],
     data[4 * (width * y + x) + 3]
   ];
 }
 
 function completionCallback(width, height, snapshot) {
   var test = testsAndExpectations[testIndex];
+  debug('Snapshot width: ' + width + ' height: ' + height);
   debug('Test ' + testIndex + ': canvas should be ' + test['description']);
   try {
     var expectation = test['expected'];
     fetchPixelAt(50, 50, width, height, snapshot);
     shouldBeCloseTo('pixel[0]', expectation[0], tolerance);
     shouldBeCloseTo('pixel[1]', expectation[1], tolerance);
     shouldBeCloseTo('pixel[2]', expectation[2], tolerance);
   } catch (e) {
     debug('error in completionCallback');
     debug(e);
     testRunner.notifyDone();
     return;
   }
 
   ++testIndex;
   window.requestAnimationFrame(nextTest);
 }
 
 function draw(r, g, b, a)
 {
   gl.clearColor(r, g, b, a);
   gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
 }
 
 main();