Reapply r9870 "Remove some initialization checks based on source positions.".

src/variables.h

 // Copyright 2011 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 85 matching lines @@
   bool has_forced_context_allocation() const {
     return force_context_allocation_;
   }
   void ForceContextAllocation() {
     ASSERT(mode_ != TEMPORARY);
     force_context_allocation_ = true;
   }
   bool is_used() { return is_used_; }
   void set_is_used(bool flag) { is_used_ = flag; }
 
+  int initializer_position() { return initializer_position_; }
+  void set_initializer_position(int pos) { initializer_position_ = pos; }
+
   bool IsVariable(Handle<String> n) const {
     return !is_this() && name().is_identical_to(n);
   }
 
   bool IsUnallocated() const { return location_ == UNALLOCATED; }
   bool IsParameter() const { return location_ == PARAMETER; }
   bool IsStackLocal() const { return location_ == LOCAL; }
   bool IsStackAllocated() const { return IsParameter() || IsStackLocal(); }
   bool IsContextSlot() const { return location_ == CONTEXT; }
   bool IsLookupSlot() const { return location_ == LOOKUP; }
@@ skipping 42 matching lines @@
 
   static int CompareIndex(Variable* const* v, Variable* const* w);
 
  private:
   Scope* scope_;
   Handle<String> name_;
   VariableMode mode_;
   Kind kind_;
   Location location_;
   int index_;
+  int initializer_position_;
 
   // If this field is set, this variable references the stored locally bound
   // variable, but it might be shadowed by variable bindings introduced by
   // non-strict 'eval' calls between the reference scope (inclusive) and the
   // binding scope (exclusive).
   Variable* local_if_not_shadowed_;
 
   // Valid as a LHS? (const and this are not valid LHS, for example)
   bool is_valid_LHS_;
 
   // Usage info.
   bool force_context_allocation_;  // set by variable resolver
   bool is_used_;
   InitializationFlag initialization_flag_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_VARIABLES_H_