Avoid creating illegal symbols in symbol_conflict_test.

tests/language/symbol_conflict_test.dart

Index: tests/language/symbol_conflict_test.dart
diff --git a/tests/language/symbol_conflict_test.dart b/tests/language/symbol_conflict_test.dart
index d896c9edb8134cffbe1cb710e2aeb01adc5d220a..10b949e7b7180d60ed9a88d41c1db2158d381f19 100644
--- a/tests/language/symbol_conflict_test.dart
+++ b/tests/language/symbol_conflict_test.dart
@@ -26,6 +26,13 @@ main() {
 /**
  The following constant was generated with the following program:
 
+   const RESERVED_WORDS = const [
+     'assert', 'break', 'case', 'catch', 'class', 'const', 'continue',
+     'default', 'do', 'else', 'enum', 'extends', 'false', 'final',
+     'finally', 'for', 'if', 'in', 'is', 'new', 'null', 'rethrow',
+     'return', 'super', 'switch', 'this', 'throw', 'true', 'try',
+     'var', 'void', 'while', 'with'];
+
    get chars sync* {
       for (int i = "a".codeUnitAt(0); i <= "z".codeUnitAt(0); i++) {
         yield new String.fromCharCodes([i]);
@@ -44,7 +51,9 @@ main() {
       // Two character symbols.
       for (String c1 in chars) {
         for (String c2 in chars) {
-          print("  const Symbol('$c1$c2'),");
+          if (!RESERVED_WORDS.contains('$c1$c2')) {

[karlklose, 2015/07/24 08:27:57]

You could actually make a multi-test that also tests that the compiler/analyzer
emits a compile-time error when encountering one of these by adding a counter id
and:
  } else {
    print("  const Symbol('$c1$c2'),  /// ${++id}: compile-time error");
  }

But that would generate to many long tests. Consider adding a
negative/multi-test in addition to this one.

[Paul Berry, 2015/07/24 13:26:25]

Actually there is already a test which verifies that "const Symbol('<keyword>')"
leads to a compile-time error: tests/corelib/symbol_reserved_word_test.dart/10. 
The VM and dart2js currently fail this test due to bugs 11669 and 19972.

I suppose that test really ought to be split up into one multitest case per
keyword (currently there's a single multitest case for all keywords, so if there
were a bug where the implementation allowed some keywords but not others, that
bug wouldn't be caught).  But considering that no one has found bug 11669
important enough to fix in two years (!) I'm having trouble getting excited
about changing anything :)

+            print("  const Symbol('$c1$c2'),");
+          }
         }
       }
       print("];");
@@ -273,7 +282,6 @@ const oneAndTwoCharacterSymbols = const [
   const Symbol('dl'),
   const Symbol('dm'),
   const Symbol('dn'),
-  const Symbol('do'),
   const Symbol('dp'),
   const Symbol('dq'),
   const Symbol('dr'),
@@ -524,7 +532,6 @@ const oneAndTwoCharacterSymbols = const [
   const Symbol('ic'),
   const Symbol('id'),
   const Symbol('ie'),
-  const Symbol('if'),
   const Symbol('ig'),
   const Symbol('ih'),
   const Symbol('ii'),
@@ -532,12 +539,10 @@ const oneAndTwoCharacterSymbols = const [
   const Symbol('ik'),
   const Symbol('il'),
   const Symbol('im'),
-  const Symbol('in'),
   const Symbol('io'),
   const Symbol('ip'),
   const Symbol('iq'),
   const Symbol('ir'),
-  const Symbol('is'),
   const Symbol('it'),
   const Symbol('iu'),
   const Symbol('iv'),