Fix resize test for offscreen canvas

OffscreenCanvas has different rules than HTMLCanvasElement

HTMLCanvasElement can have width or height set to negative numbers
and will then set the canvas width or height to its default,
300 for width, 150 for height

OffscreenCanvas will throw an error with a negative width or height.

For OffscreenCanvas, all 3 major browsers do not reset the canvas
if width or height are set to the same value they already are

For HTMLCanvasElement, Beacuse there are issues with requestAnimationFrame,
ResizeObserver, and compositing the page, it seems like, at least for
HTMLCanvasElement, all 3 APIs should behave the same.

src/webgpu/web_platform/canvas/getCurrentTexture.spec.ts

@@ -293,28 +293,31 @@ g.test('resize')
       exp: { R: 0, G: 0, B: 0, A: 0 },
     });
 
-    // Ensure canvas goes back to defaults when set to negative numbers.
-    ctx.canvas.width = -1;
-    currentTexture = ctx.getCurrentTexture();
-    t.expect(currentTexture.width === 300);
-    t.expect(currentTexture.height === 4);
-
-    ctx.canvas.height = -1;
-    currentTexture = ctx.getCurrentTexture();
-    t.expect(currentTexture.width === 300);
-    t.expect(currentTexture.height === 150);
-    prevTexture = currentTexture;
-
-    // Setting the canvas width and height values to their current values should
-    // still trigger a change in the texture.
-    const { width, height } = ctx.canvas;
-    ctx.canvas.width = width;
-    ctx.canvas.height = height;
-
-    t.expectTextureDestroyed(prevTexture);
-
-    currentTexture = ctx.getCurrentTexture();
-    t.expect(prevTexture !== currentTexture);
+    // HTMLCanvasElement behaves differently than OffscreenCanvas
+    if (t.params.canvasType === 'onscreen') {
+      // Ensure canvas goes back to defaults when set to negative numbers.
+      ctx.canvas.width = -1;
+      currentTexture = ctx.getCurrentTexture();
+      t.expect(currentTexture.width === 300);
+      t.expect(currentTexture.height === 4);
+
+      ctx.canvas.height = -1;
+      currentTexture = ctx.getCurrentTexture();
+      t.expect(currentTexture.width === 300);
+      t.expect(currentTexture.height === 150);
+
+      // Setting the canvas width and height values to their current values should
+      // still trigger a change in the texture.
+      prevTexture = ctx.getCurrentTexture();
+      const { width, height } = ctx.canvas;
+      ctx.canvas.width = width;
+      ctx.canvas.height = height;
+
+      t.expectTextureDestroyed(prevTexture);
+
+      currentTexture = ctx.getCurrentTexture();
+      t.expect(prevTexture !== currentTexture);
+    }
   });
 
 g.test('expiry')