Removed unused variable to fix Linux build

src/execution.cc

 // Copyright 2006-2008 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 573 matching lines @@
 #ifdef ENABLE_DEBUGGER_SUPPORT
 Object* Execution::DebugBreakHelper() {
   // Just continue if breaks are disabled.
   if (Debug::disable_break()) {
     return Heap::undefined_value();
   }
 
   // Collect the break state before clearing the flags.
   bool debug_command_only =
       StackGuard::IsDebugCommand() && !StackGuard::IsDebugBreak();
-  bool is_debug_break = StackGuard::IsDebugBreak();
 
   // Clear the debug request flags.
   StackGuard::Continue(DEBUGBREAK);
   StackGuard::Continue(DEBUGCOMMAND);
 
   HandleScope scope;
   // Enter the debugger. Just continue if we fail to enter the debugger.
   EnterDebugger debugger;
   if (debugger.FailedToEnter()) {
     return Heap::undefined_value();
@@ skipping 38 matching lines @@
   // All allocation spaces other than NEW_SPACE have the same effect.
   Heap::CollectAllGarbage();
   return v8::Undefined();
 }
 
 
 static GCExtension kGCExtension;
 v8::DeclareExtension kGCExtensionDeclaration(&kGCExtension);
 
 } }  // namespace v8::internal