Perform the illegal redeclaration check earlier in graph building.

src/compiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 336 matching lines @@
   if ((scope->num_parameters() + 1) > parameter_limit) {
     return AbortAndDisableOptimization(kTooManyParameters);
   }
 
   const int locals_limit = LUnallocated::kMaxFixedSlotIndex;
   if (info()->is_osr() &&
       scope->num_parameters() + 1 + scope->num_stack_slots() > locals_limit) {
     return AbortAndDisableOptimization(kTooManyParametersLocals);
   }
 
+  if (scope->HasIllegalRedeclaration()) {
+    return AbortAndDisableOptimization(kFunctionWithIllegalRedeclaration);
+  }
+
   // Take --hydrogen-filter into account.
   if (!info()->closure()->PassesFilter(FLAG_hydrogen_filter)) {
     return AbortOptimization(kHydrogenFilter);
   }
 
   // Recompile the unoptimized version of the code if the current version
   // doesn't have deoptimization support. Alternatively, we may decide to
   // run the full code generator to get a baseline for the compile-time
   // performance of the hydrogen-based compiler.
   bool should_recompile = !info()->shared_info()->has_deoptimization_support();
@@ skipping 939 matching lines @@
   AllowHandleDereference allow_deref;
   bool tracing_on = info()->IsStub()
       ? FLAG_trace_hydrogen_stubs
       : (FLAG_trace_hydrogen &&
          info()->closure()->PassesFilter(FLAG_trace_hydrogen_filter));
   return (tracing_on &&
       OS::StrChr(const_cast<char*>(FLAG_trace_phase), name_[0]) != NULL);
 }
 
 } }  // namespace v8::internal