First stab at parsing redirecting constructors.

lib/compiler/implementation/scanner/parser.dart

Index: lib/compiler/implementation/scanner/parser.dart
diff --git a/lib/compiler/implementation/scanner/parser.dart b/lib/compiler/implementation/scanner/parser.dart
index 4f4f5ddba2aba43b2f61400ae36a5585d69f63d0..41dcc83035e84a3c49731b8fb6f5ea96d17f2a03 100644
--- a/lib/compiler/implementation/scanner/parser.dart
+++ b/lib/compiler/implementation/scanner/parser.dart
@@ -916,7 +916,11 @@ class Parser {
       token = parseIdentifier(token.next);
     }
     token = parseFormalParameters(token);
-    token = parseFunctionBody(token, false);
+    if (optional('=', token)) {
+      token = parseRedirectingFactoryBody(token);
+    } else {
+      token = parseFunctionBody(token, false);
+    }
     listener.endFactoryMethod(start, period, token);
     return token.next;
   }
@@ -991,6 +995,21 @@ class Parser {
     return isBlock ? token.next : token;
   }
 
+  Token parseRedirectingFactoryBody(Token token) {
+    listener.beginRedirectingFactoryBody(token);
+    assert('=' === token.stringValue);

[ahe, 2012/10/05 08:23:20]

assert(optional('=', token));

I should clean up the other uses similar to this.

[Lasse Reichstein Nielsen, 2012/10/09 09:46:54]

Done.

+    Token equals = token;
+    token = parseType(token.next);
+    Token dot = null;
+    if (optional('.', token)) {
+      dot = token;
+      token = parseIdentifier(token.next);
+    }
+    expectSemicolon(token);
+    listener.endRedirectingFactoryBody(equals, dot, token);
+    return token;

[ahe, 2012/10/05 08:23:20]

You should consume the semicolon token if you require it.

[Lasse Reichstein Nielsen, 2012/10/09 09:46:54]

I don't think that's compatible with parseFunctionBody.
In parseFunctionBody, the semicolon is not consumed, and the calling methods use
the returned token (the semicolon) as the end-token of their calls to
endFunction. The parseRedirectingFactoryBody method is used in the same place as
a call to parseFunctionBody, and seems to need the same behavior.

+  }
+
   Token parseFunctionBody(Token token, bool isExpression) {
     if (optional(';', token)) {
       listener.endFunctionBody(0, null, token);