Fix description in index.html / manifest.json getting double quoted (#131842)

This PR adjusts the quoting of the project description not not apply twice in the index.html / manifest.json of web builds.

*List which issues are fixed by this PR. You must list at least one issue.*
Fixes https://github.com/flutter/flutter/issues/131834

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*

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

@@ -389,7 +389,7 @@ abstract class CreateBase extends FlutterCommand {
       'macosIdentifier': appleIdentifier,
       'linuxIdentifier': linuxIdentifier,
       'windowsIdentifier': windowsIdentifier,
-      'description': projectDescription != null ? escapeYamlString(projectDescription) : null,
+      'description': projectDescription,
       'dartSdk': '$flutterRoot/bin/cache/dart-sdk',
       'androidMinApiLevel': android_common.minApiLevel,
       'androidSdkVersion': kAndroidSdkMinVersion,

packages/flutter_tools/lib/src/template.dart

@@ -361,7 +361,13 @@ class Template {
           context['androidIdentifier'] = _escapeKotlinKeywords(androidIdentifier);
         }
 
-        final String renderedContents = _templateRenderer.renderString(templateContents, context);
+        // Use a copy of the context,
+        // since the original is used in rendering other templates.
+        final Map<String, Object?> localContext = finalDestinationFile.path.endsWith('.yaml')
+          ? _createEscapedContextCopy(context)
+          : context;
+
+        final String renderedContents = _templateRenderer.renderString(templateContents, localContext);
 
         finalDestinationFile.writeAsStringSync(renderedContents);
 
@@ -377,6 +383,21 @@ class Template {
   }
 }
 
+/// Create a copy of the given [context], escaping its values when necessary.
+///
+/// Returns the copied context.
+Map<String, Object?> _createEscapedContextCopy(Map<String, Object?> context) {
+  final Map<String, Object?> localContext = Map<String, Object?>.of(context);
+
+  final String? description = localContext['description'] as String?;
+
+  if (description != null && description.isNotEmpty) {
+    localContext['description'] = escapeYamlString(description);
+  }
+
+  return localContext;
+}
+
 String _escapeKotlinKeywords(String androidIdentifier) {
   final List<String> segments = androidIdentifier.split('.');
   final List<String> correctedSegments = segments.map(

packages/flutter_tools/test/commands.shard/permeable/create_test.dart

@@ -3384,6 +3384,32 @@ void main() {
     FeatureFlags: () => TestFeatureFlags(),
     Logger: () => logger,
   });
+
+  testUsingContext('Does not double quote description in index.html on web', () async {
+    await _createProject(
+      projectDir,
+      <String>['--no-pub', '--platforms=web'],
+      <String>['pubspec.yaml', 'web/index.html'],
+    );
+
+    final String rawIndexHtml = await projectDir.childDirectory('web').childFile('index.html').readAsString();
+    const String expectedDescription = '<meta name="description" content="A new Flutter project.">';
+
+    expect(rawIndexHtml.contains(expectedDescription), isTrue);
+  });
+
+  testUsingContext('Does not double quote description in manifest.json on web', () async {
+    await _createProject(
+      projectDir,
+      <String>['--no-pub', '--platforms=web'],
+      <String>['pubspec.yaml', 'web/manifest.json'],
+    );
+
+    final String rawManifestJson = await projectDir.childDirectory('web').childFile('manifest.json').readAsString();
+    const String expectedDescription = '"description": "A new Flutter project."';
+
+    expect(rawManifestJson.contains(expectedDescription), isTrue);
+  });
 }
 
 Future<void> _createProject(