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

third_party/WebKit/LayoutTests/fast/canvas/canvas-lineWidth.js

-// Compare sections of a <canvas> to assert they are identical, or nearly so.
-function compareRows(ctx, y0, y1, width, height, allowableDifference) {
-    var data0 = ctx.getImageData(0, y0, width, height).data;
-    var data1 = ctx.getImageData(0, y1, width, height).data;
-    for (var i = 0, il = data0.length; i < il; ++i) {
-        if (Math.abs(data0[i] - data1[i]) > allowableDifference) {
-            testFailed("Pixel at " + i + " should be within " + allowableDifference +
-                " of " + data0[i] + " but was " + data1[i]);
-            break;
-        }
-    }
-}
-
-description("Test the default lineWidth is consistent.");
-
-ctx = document.getElementById("canvas").getContext("2d");
-
-ctx.strokeStyle = 'blue';
-
-for (var j = 0; j < 3; ++j) {
-    ctx.beginPath();
-    for (var i = 0; i < 60; ++i) {
-        var x = i * 10;
-        var y = j * 100 + 30 + (i % 15);
-        if (i == 0) {
-            ctx.moveTo(x, y);
-        } else {
-            ctx.lineTo(x, y);
-        }
-    }
-    ctx.stroke();
-
-    if (j == 0) {
-        shouldBe("ctx.lineWidth", "1");
-        ctx.lineWidth = ctx.lineWidth;
-        shouldBe("ctx.lineWidth", "1");
-    } else {
-        shouldBe("ctx.lineWidth", "1");
-        ctx.lineWidth = 1;
-        shouldBe("ctx.lineWidth", "1");
-    }
-}
-
-// Make sure that all rows are nearly identical.
-// (Tiny variations are OK.)
-compareRows(ctx, 0, 100, 600, 100, 1);
-compareRows(ctx, 0, 200, 600, 100, 1);