Scheduling Profiler: Improve import performance by dropping IE support

packages/react-devtools-scheduling-profiler/babel.config.js

@@ -0,0 +1,44 @@
+const chromeManifest = require('../react-devtools-extensions/chrome/manifest.json');
+const firefoxManifest = require('../react-devtools-extensions/firefox/manifest.json');
+
+const minChromeVersion = parseInt(chromeManifest.minimum_chrome_version, 10);
+const minFirefoxVersion = parseInt(
+  firefoxManifest.applications.gecko.strict_min_version,
+  10,
+);
+validateVersion(minChromeVersion);
+validateVersion(minFirefoxVersion);
+
+function validateVersion(version) {
+  if (version > 0 && version < 200) {
+    return;
+  }
+  throw new Error('Suspicious browser version in manifest: ' + version);
+}
+
+module.exports = api => {
+  const isTest = api.env('test');
+  const targets = {};
+  if (isTest) {
+    targets.node = 'current';
+  } else {
+    targets.chrome = minChromeVersion.toString();
+    targets.firefox = minFirefoxVersion.toString();
+    // We won't support IE because that'll double profile import times.
+  }
+  const plugins = [
+    ['@babel/plugin-transform-flow-strip-types'],
+    ['@babel/plugin-proposal-class-properties', {loose: false}],
+  ];
+  if (process.env.NODE_ENV !== 'production') {
+    plugins.push(['@babel/plugin-transform-react-jsx-source']);
+  }
+  return {
+    plugins,
+    presets: [
+      ['@babel/preset-env', {targets}],
+      '@babel/preset-react',
+      '@babel/preset-flow',
+    ],
+  };
+};

packages/react-devtools-scheduling-profiler/webpack.config.js

@@ -27,12 +27,7 @@ const DEVTOOLS_VERSION = getVersionString();
 const imageInlineSizeLimit = 10000;
 
 const babelOptions = {
-  configFile: resolve(
-    __dirname,
-    '..',
-    'react-devtools-shared',
-    'babel.config.js',
-  ),
+  configFile: resolve(__dirname, 'babel.config.js'),
   plugins: shouldUseDevServer
     ? [resolve(builtModulesDir, 'react-refresh/babel')]
     : [],