[es6] implement destructuring assignment

src/crankshaft/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/crankshaft/hydrogen.h"
 
 #include <sstream>
 
 #include "src/allocation-site-scopes.h"
 #include "src/ast-numbering.h"
@@ skipping 5843 matching lines @@
                            max_properties)) {
           return false;
         }
       }
     }
   }
   return true;
 }
 
 
+void HOptimizedGraphBuilder::VisitAssignmentPattern(AssignmentPattern* expr) {

[adamk, 2015/11/20 22:42:58]

I don't think this is sufficient to bail out of Crankshaft. I suspect you need
to modify VisitAssignment, otherwise you'll get DCHECK failures there.

+  DCHECK(!HasStackOverflow());
+  DCHECK(current_block() != NULL);
+  DCHECK(current_block()->HasPredecessor());
+  return Bailout(kAssignmentPattern);
+}
+
+
 void HOptimizedGraphBuilder::VisitObjectLiteral(ObjectLiteral* expr) {
   DCHECK(!HasStackOverflow());
   DCHECK(current_block() != NULL);
   DCHECK(current_block()->HasPredecessor());
 
   Handle<JSFunction> closure = function_state()->compilation_info()->closure();
   HInstruction* literal;
 
   // Check whether to use fast or slow deep-copying for boilerplate.
   int max_properties = kMaxFastLiteralProperties;
@@ skipping 7764 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8