Fix regexp that strips invalid characters from the project identifier

Fixes #3835

examples/hello_world/ios/Info.plist

@@ -7,7 +7,7 @@
 	<key>CFBundleExecutable</key>
 	<string>Runner</string>
 	<key>CFBundleIdentifier</key>
-	<string>io.flutter.example.hello_world</string>
+	<string>io.flutter.example.helloworld</string>
 	<key>CFBundleInfoDictionaryVersion</key>
 	<string>6.0</string>
 	<key>CFBundleName</key>

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

@@ -193,7 +193,7 @@ String _createAndroidIdentifier(String name) {
 
 String _createUTIIdentifier(String name) {
   // Create a UTI (https://en.wikipedia.org/wiki/Uniform_Type_Identifier) from a base name
-  RegExp disallowed = new RegExp(r"[^a-zA-Z0-9\-.\u0080-\uffff]+");
+  RegExp disallowed = new RegExp(r"[^a-zA-Z0-9\-\.\u0080-\uffff]+");
   name = camelCase(name).replaceAll(disallowed, '');
   name = name.isEmpty ? 'untitled' : name;
   return 'com.yourcompany.$name';