Properly handle cascades in top-level functions

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 20275)
+++ runtime/vm/parser.cc	(working copy)
@@ -9891,9 +9891,15 @@
 
 void Parser::SkipSelectors() {
   while (true) {
-    if ((CurrentToken() == Token::kPERIOD) ||
-        (CurrentToken() == Token::kCASCADE)) {
+    if (CurrentToken() == Token::kCASCADE) {
       ConsumeToken();
+      if (CurrentToken() == Token::kLBRACK) {
+        continue;  // Consume [ in next loop iteration.
+      } else {
+        ExpectIdentifier("identifier or [ expected after ..");
+      }
+    } else if (CurrentToken() == Token::kPERIOD) {
+      ConsumeToken();
       ExpectIdentifier("identifier expected");
     } else if (CurrentToken() == Token::kLBRACK) {
       ConsumeToken();