Simplify the desugaring of catch clauses.

runtime/vm/flow_graph_builder.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_builder.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/class_finalizer.h"
@@ skipping 3579 matching lines @@
 
   CatchBlockEntryInstr* catch_entry =
       new CatchBlockEntryInstr(owner()->AllocateBlockId(),
                                catch_handler_index,
                                catch_block->handler_types(),
                                try_handler_index,
                                catch_block->exception_var(),
                                catch_block->stacktrace_var(),
                                catch_block->needs_stacktrace());
   owner()->AddCatchEntry(catch_entry);
-  ASSERT(!for_catch.is_open());
   AppendFragment(catch_entry, for_catch);
 
-  JoinEntryInstr* join = node->end_catch_label()->join_for_continue();
-  if (join != NULL) {
+  if (for_catch.is_open()) {
+    JoinEntryInstr* join = new JoinEntryInstr(owner()->AllocateBlockId(),
+                                              original_handler_index);
+    for_catch.Goto(join);
     if (is_open()) Goto(join);
     exit_ = join;
   }
 
   if (finally_block != NULL) {
     // Create a handler for the code in the catch block, containing the
     // code in the finally block.
     owner()->set_try_index(original_handler_index);
     EffectGraphVisitor for_finally(owner());
     for_finally.BuildRestoreContext(catch_block->context_var());
@@ skipping 268 matching lines @@
   intptr_t len = OS::SNPrint(NULL, 0, kFormat, function_name, reason) + 1;
   char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart