[tools, web] Make sure to copy the dump-info file if dump-info is used (#165013)

Also fixed the wording of the dump-info build flag

Author: kevmoo

packages/flutter_tools/lib/src/build_system/targets/web.dart

@@ -252,6 +252,12 @@ class Dart2JSTarget extends Dart2WebTarget {
             return true;
           }
         }
+
+        if (compilerConfig.dumpInfo) {
+          if (file.basename == 'main.dart.js.info.json') {
+            return true;
+          }
+        }
         return false;
       });
 

packages/flutter_tools/lib/src/commands/build_web.dart

@@ -95,7 +95,7 @@ class BuildWebCommand extends BuildSubCommand {
       negatable: false,
       help:
           'Passes "--dump-info" to the Javascript compiler which generates '
-          'information about the generated code is a .js.info.json file.',
+          'information about the generated code in main.dart.js.info.json.',
     );
     argParser.addFlag(
       'no-frequency-based-minification',

packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart

@@ -227,14 +227,18 @@ name: foo
         ..createSync(recursive: true)
         ..writeAsStringSync('A');
       environment.buildDir.childFile('main.dart.js').createSync();
+      environment.buildDir.childFile('main.dart.js.info.json').createSync();
       environment.buildDir.childFile('main.dart.js.map').createSync();
       environment.buildDir.childFile('main.dart.js_1.part.js').createSync();
       environment.buildDir.childFile('main.dart.js_1.part.js.map').createSync();
 
-      await WebReleaseBundle(<WebCompilerConfig>[const JsCompilerConfig()]).build(environment);
+      await WebReleaseBundle(<WebCompilerConfig>[
+        const JsCompilerConfig(dumpInfo: true),
+      ]).build(environment);
 
       expect(environment.outputDir.childFile('foo.txt').readAsStringSync(), 'A');
       expect(environment.outputDir.childFile('main.dart.js').existsSync(), true);
+      expect(environment.outputDir.childFile('main.dart.js.info.json').existsSync(), true);
       expect(environment.outputDir.childFile('main.dart.js.map').existsSync(), true);
       expect(environment.outputDir.childFile('main.dart.js_1.part.js').existsSync(), true);
       expect(environment.outputDir.childFile('main.dart.js_1.part.js.map').existsSync(), true);