Reject non-ASCII identifiers.

dart/lib/compiler/implementation/scanner/token.dart

Index: dart/lib/compiler/implementation/scanner/token.dart
diff --git a/dart/lib/compiler/implementation/scanner/token.dart b/dart/lib/compiler/implementation/scanner/token.dart
index 6821a14f2e6c338e8bea8be201fac6fb148128cf..7646e4ef6cec1bf630b10de77e386f68acedd7a4 100644
--- a/dart/lib/compiler/implementation/scanner/token.dart
+++ b/dart/lib/compiler/implementation/scanner/token.dart
@@ -6,6 +6,7 @@ const int EOF_TOKEN = 0;
 
 const int KEYWORD_TOKEN = $k;
 const int IDENTIFIER_TOKEN = $a;
+const int BAD_INPUT_TOKEN = $X;
 const int DOUBLE_TOKEN = $d;
 const int INT_TOKEN = $i;
 const int HEXADECIMAL_TOKEN = $x;
@@ -459,6 +460,10 @@ const PrecedenceInfo EOF_INFO =
 const PrecedenceInfo IDENTIFIER_INFO =
   const PrecedenceInfo(const SourceString('identifier'), 0, IDENTIFIER_TOKEN);
 
+const PrecedenceInfo BAD_INPUT_INFO =
+  const PrecedenceInfo(const SourceString('malformed input'), 0,
+                       BAD_INPUT_TOKEN);
+
 const PrecedenceInfo OPEN_PAREN_INFO =
   const PrecedenceInfo(const SourceString('('), POSTFIX_PRECEDENCE,
                        OPEN_PAREN_TOKEN);