Convert raw strings in pub (and apidoc) to new syntax.

utils/tests/pub/pub_update_test.dart

Index: utils/tests/pub/pub_update_test.dart
diff --git a/utils/tests/pub/pub_update_test.dart b/utils/tests/pub/pub_update_test.dart
index 5c1898f500e64c489f72d92582eba8b750a197c8..8f9128d8980082fc4f38c5a639028b7e78702cb5 100644
--- a/utils/tests/pub/pub_update_test.dart
+++ b/utils/tests/pub/pub_update_test.dart
@@ -15,7 +15,7 @@ main() {
       dir(appPath, []).scheduleCreate();
 
       schedulePub(args: ['update'],
-          error: const RegExp(@'^Could not find a file named "pubspec.yaml"'),
+          error: const RegExp(r'^Could not find a file named "pubspec.yaml"'),
           exitCode: 1);
 
       run();
@@ -27,8 +27,8 @@ main() {
       ]).scheduleCreate();
 
       schedulePub(args: ['update'],
-          error: const RegExp(@'^pubspec.yaml is missing the required "name" '
-              @'field \(e\.g\. "name: myapp"\)\.'),
+          error: const RegExp(r'^pubspec.yaml is missing the required "name" '
+              r'field \(e\.g\. "name: myapp"\)\.'),
           exitCode: 1);
 
       run();
@@ -44,7 +44,7 @@ main() {
     ]).scheduleCreate();
 
     schedulePub(args: ['update'],
-        output: const RegExp(@"Dependencies updated!$"));
+        output: const RegExp(r"Dependencies updated!$"));
 
     dir(packagesPath, [
       dir("myapp_name", [
@@ -63,7 +63,7 @@ main() {
     ]).scheduleCreate();
 
     schedulePub(args: ['update'],
-        output: const RegExp(@"Dependencies updated!$"));
+        output: const RegExp(r"Dependencies updated!$"));
 
     dir(packagesPath, [
       nothing("myapp_name")