Fix source generation for strings that have \$ in them.

runtime/bin/main.cc

Index: runtime/bin/main.cc
===================================================================
--- runtime/bin/main.cc	(revision 19996)
+++ runtime/bin/main.cc	(working copy)
@@ -863,18 +863,18 @@
       if (Dart_IsError(result)) {
         return ErrorExit("%s\n", Dart_GetError(result));
       }
+    } else {
+      // Lookup and invoke the top level main function.
+      result = Dart_Invoke(library, DartUtils::NewString("main"), 0, NULL);
+      if (Dart_IsError(result)) {
+        return ErrorExit("%s\n", Dart_GetError(result));
+      }
+      // Keep handling messages until the last active receive port is closed.
+      result = Dart_RunLoop();
+      if (Dart_IsError(result)) {
+        return ErrorExit("%s\n", Dart_GetError(result));
+      }
     }
-
-    // Lookup and invoke the top level main function.
-    result = Dart_Invoke(library, DartUtils::NewString("main"), 0, NULL);
-    if (Dart_IsError(result)) {
-      return ErrorExit("%s\n", Dart_GetError(result));
-    }
-    // Keep handling messages until the last active receive port is closed.
-    result = Dart_RunLoop();
-    if (Dart_IsError(result)) {
-      return ErrorExit("%s\n", Dart_GetError(result));
-    }
   }
 
   Dart_ExitScope();