Fix for extra space preceding the 'on' keyword in a catch clause (dartbug.com/15454).

pkg/analyzer/test/services/formatter_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:unittest/unittest.dart';
 
 import 'package:analyzer/src/generated/java_core.dart' show CharSequence;
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/services/formatter_impl.dart';
 import 'package:analyzer/src/services/writer.dart';
@@ skipping 818 matching lines @@
         'doSomething();\n'
         '} catch (e) {\n'
         'print(e);\n'
         '}',
         'try {\n'
         '  doSomething();\n'
         '} catch (e) {\n'
         '  print(e);\n'
         '}'
       );
+      expectStmtFormatsTo(
+          'try{\n'
+          'doSomething();\n'
+          '}on Exception catch (e){\n'
+          'print(e);\n'
+          '}',
+          'try {\n'
+          '  doSomething();\n'
+          '} on Exception catch (e) {\n'
+          '  print(e);\n'
+          '}'
+      );
     });
 
     test('stmt (binary/ternary ops)', () {
       expectStmtFormatsTo(
         'var a = 1 + 2 / (3 * -b);',
         'var a = 1 + 2 / (3 * -b);'
       );
       expectStmtFormatsTo(
         'var c = !condition == a > b;',
         'var c = !condition == a > b;'
@@ skipping 287 matching lines @@
     expect(() => new TokenStreamComparator(null, t1, t2).verifyEquals(),
     throwsA(new isInstanceOf<FormatterException>()));
 
 expectCUFormatsTo(src, expected, {transforms: true}) =>
     expect(formatCU(src, options: new FormatterOptions(
         codeTransforms: transforms)).source, equals(expected));
 
 expectStmtFormatsTo(src, expected, {transforms: true}) =>
     expect(formatStatement(src, options:
       new FormatterOptions(codeTransforms: transforms)), equals(expected));