feat: use modern browser target during dev

This speeds up development hot-reload time.

Closes #12

Author: swashata

packages/scripts/__tests__/config/__snapshots__/WebpackConfigHelper.spec.ts.snap

@@ -39,6 +39,13 @@ Object {
                 "@wpackio/base",
                 Object {
                   "hasReact": true,
+                  "presetEnv": Object {
+                    "targets": Object {
+                      "chrome": "69",
+                      "edge": "17",
+                      "firefox": "62",
+                    },
+                  },
                 },
               ],
             ],
@@ -60,6 +67,13 @@ Object {
                 "@wpackio/base",
                 Object {
                   "hasReact": true,
+                  "presetEnv": Object {
+                    "targets": Object {
+                      "chrome": "69",
+                      "edge": "17",
+                      "firefox": "62",
+                    },
+                  },
                 },
               ],
               Array [

packages/scripts/src/config/WebpackConfigHelper.ts

@@ -303,12 +303,27 @@ ${bannerConfig.copyrightText}${bannerConfig.credit ? creditNote : ''}`,
 	 */
 	public getModule(): webpack.Module {
 		const { hasReact, hasSass, hasFlow } = this.config;
+		const wpackioBabelOptions: PresetOptions = {
+			hasReact,
+		};
+		// Push targets to babel-preset-env if this is dev
+		// We target only the latest chrome and firefox for
+		// greater speed
+		if (this.isDev) {
+			wpackioBabelOptions.presetEnv = {
+				targets: {
+					chrome: '69',
+					firefox: '62',
+					edge: '17',
+				},
+			};
+		}
 		// create the babel rules for es6+ code
 		const jsPresets: babelPreset[] = [
 			[
 				'@wpackio/base',
 				this.getBabelPresetOptions(
-					{ hasReact },
+					wpackioBabelOptions,
 					this.config.jsBabelPresetOptions
 				),
 			],
@@ -343,7 +358,7 @@ ${bannerConfig.copyrightText}${bannerConfig.credit ? creditNote : ''}`,
 			[
 				'@wpackio/base',
 				this.getBabelPresetOptions(
-					{ hasReact },
+					wpackioBabelOptions,
 					this.config.tsBabelPresetOptions
 				),
 			],