fix: Revert "feat: Corner Smoothing CSS rule" (#46231)

Revert "feat: Corner Smoothing CSS rule (#45185)"

This reverts commit b75e802280.

spec/api-corner-smoothing-spec.ts

@@ -1,156 +0,0 @@
-import { NativeImage, nativeImage } from 'electron/common';
-import { BrowserWindow } from 'electron/main';
-
-import { AssertionError, expect } from 'chai';
-
-import path = require('node:path');
-
-import { createArtifact } from './lib/artifacts';
-import { ifdescribe } from './lib/spec-helpers';
-import { closeAllWindows } from './lib/window-helpers';
-
-const FIXTURE_PATH = path.resolve(
-  __dirname,
-  'fixtures',
-  'api',
-  'corner-smoothing'
-);
-
-/**
- * Rendered images may "match" but slightly differ due to rendering artifacts
- * like anti-aliasing and vector path resolution, among others. This tolerance
- * is the cutoff for whether two images "match" or not.
- *
- * From testing, matching images were found to have an average global difference
- * up to about 1.3 and mismatched images were found to have a difference of at
- * least about 7.3.
- *
- * See the documentation on `compareImages` for more information.
- */
-const COMPARISON_TOLERANCE = 2.5;
-
-/**
- * Compares the average global difference of two images to determine if they
- * are similar enough to "match" each other.
- *
- * "Average global difference" is the average difference of pixel components
- * (RGB each) across an entire image.
- *
- * The cutoff for matching/not-matching is defined by the `COMPARISON_TOLERANCE`
- * constant.
- */
-function compareImages (img1: NativeImage, img2: NativeImage): boolean {
-  expect(img1.getSize()).to.deep.equal(
-    img2.getSize(),
-    'Cannot compare images with different sizes'
-  );
-
-  const bitmap1 = img1.toBitmap();
-  const bitmap2 = img2.toBitmap();
-
-  const { width, height } = img1.getSize();
-
-  let totalDiff = 0;
-  for (let x = 0; x < width; x++) {
-    for (let y = 0; y < height; y++) {
-      const index = (x + y * width) * 4;
-      const pixel1 = bitmap1.subarray(index, index + 4);
-      const pixel2 = bitmap2.subarray(index, index + 4);
-      const diff =
-        Math.abs(pixel1[0] - pixel2[0]) +
-        Math.abs(pixel1[1] - pixel2[1]) +
-        Math.abs(pixel1[2] - pixel2[2]);
-      totalDiff += diff;
-    }
-  }
-
-  const avgDiff = totalDiff / (width * height);
-  return avgDiff <= COMPARISON_TOLERANCE;
-}
-
-/**
- * Recipe for tests.
- *
- * The page is rendered, captured as an image, then compared to an expected
- * result image.
- */
-async function pageCaptureTestRecipe (
-  pagePath: string,
-  expectedImgPath: string,
-  artifactName: string,
-  cornerSmoothingAvailable: boolean = true
-): Promise<void> {
-  const w = new BrowserWindow({
-    show: false,
-    width: 800,
-    height: 600,
-    useContentSize: true,
-    webPreferences: {
-      enableCornerSmoothingCSS: cornerSmoothingAvailable
-    }
-  });
-  await w.loadFile(pagePath);
-  w.show();
-
-  // Wait for a render frame to prepare the page.
-  await w.webContents.executeJavaScript(
-    'new Promise((resolve) => { requestAnimationFrame(() => resolve()); })'
-  );
-
-  const actualImg = await w.webContents.capturePage();
-  expect(actualImg.isEmpty()).to.be.false('Failed to capture page image');
-
-  const expectedImg = nativeImage.createFromPath(expectedImgPath);
-  expect(expectedImg.isEmpty()).to.be.false(
-    'Failed to read expected reference image'
-  );
-
-  const matches = compareImages(actualImg, expectedImg);
-  if (!matches) {
-    const artifactFileName = `corner-rounding-expected-${artifactName}.png`;
-    await createArtifact(artifactFileName, actualImg.toPNG());
-
-    throw new AssertionError(
-      `Actual image did not match expected reference image. Actual: "${artifactFileName}" in artifacts, Expected: "${path.relative(
-        path.resolve(__dirname, '..'),
-        expectedImgPath
-      )}" in source`
-    );
-  }
-}
-
-// FIXME: these tests rely on live rendering results, which are too variable to
-// reproduce outside of CI, primarily due to display scaling.
-ifdescribe(!!process.env.CI)('-electron-corner-smoothing', () => {
-  afterEach(async () => {
-    await closeAllWindows();
-  });
-
-  describe('shape', () => {
-    for (const available of [true, false]) {
-      it(`matches the reference with web preference = ${available}`, async () => {
-        await pageCaptureTestRecipe(
-          path.join(FIXTURE_PATH, 'shape', 'test.html'),
-          path.join(FIXTURE_PATH, 'shape', `expected-${available}.png`),
-          `shape-${available}`,
-          available
-        );
-      });
-    }
-  });
-
-  describe('system-ui keyword', () => {
-    const { platform } = process;
-    it(`matches the reference for platform = ${platform}`, async () => {
-      await pageCaptureTestRecipe(
-        path.join(FIXTURE_PATH, 'system-ui-keyword', 'test.html'),
-        path.join(
-          FIXTURE_PATH,
-          'system-ui-keyword',
-          `expected-${platform}.png`
-        ),
-        `system-ui-${platform}`
-      );
-    });
-  });
-});