Use testharness.js instead of js-test.js in LayoutTests/fast/canvas tests.

third_party/WebKit/LayoutTests/fast/canvas/canvas-radial-gradient-spreadMethod.js

-description("Series of tests to ensure correct behaviour of spreadMethod to a radial gradient.");
-var ctx = document.createElement('canvas').getContext('2d');
-
-var radgrad = ctx.createRadialGradient(80,90,90,80,50,100);
-radgrad.addColorStop(0, 'green');
-radgrad.addColorStop(1, 'green');
-
-ctx.fillStyle = radgrad;
-ctx.fillRect(0, 0, 100, 100);
-var imageData = ctx.getImageData(0, 0, 100, 100);
-var imgdata = imageData.data;
-shouldBe("imgdata[4]", "0");
-shouldBe("imgdata[5]", "128");
-shouldBe("imgdata[6]", "0");
-shouldBe("imgdata[7]", "255");