Parse unary plus corretly (i.e., by ignoring it when it's valid).

frog/leg/scanner/parser.dart

Index: frog/leg/scanner/parser.dart
diff --git a/frog/leg/scanner/parser.dart b/frog/leg/scanner/parser.dart
index b911d1d82de61e55a730522eafd15e6ae539613f..26413dfb3296c10ea833909beb7c2de3388b597d 100644
--- a/frog/leg/scanner/parser.dart
+++ b/frog/leg/scanner/parser.dart
@@ -942,10 +942,22 @@ class Parser {
   Token parseUnaryExpression(Token token) {
     String value = token.stringValue;
     // Prefix:
-    if ((value === '!') ||
-        (value === '+') || // TODO(ahe): Being removed from specification.
-        (value === '-') ||
-        (value === '~')) {
+    if (value === '+') {
+      // Dart only allows "prefix plus" as an initial part of a
+      // decimal literal. We scan it as a separate token and then throw
+      // it away here when we know that we have a unary plus, not a

[ahe, 2012/02/03 13:19:11]

We are not throwing it away anymore :-)

+      // binary one.
+      Token operator = token;
+      Token next = token.next;
+      if (next.charOffset !== token.charOffset + 1 ||
+          (next.kind !== INT_TOKEN && next.kind !== DOUBLE_TOKEN)) {
+        listener.recoverableError("Unexpected token '+'", token: token);
+      }
+      token = parsePrecedenceExpression(next, POSTFIX_PRECEDENCE);
+      listener.handleUnaryPrefixExpression(operator);
+    } else if ((value === '!') ||
+               (value === '-') ||
+               (value === '~')) {
       Token operator = token;
       // Right associative, so we recurse at the same precedence
       // level.