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

src/parser.cc

 // 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 1755 matching lines @@
     // which the variable or constant is declared. Only function variables have
     // an initial value in the declaration (because they are initialized upon
     // entering the function).
     //
     // If we have a const declaration, in an inner scope, the proxy is always
     // bound to the declared variable (independent of possibly surrounding with
     // statements).
     // For let/const declarations in harmony mode, we can also immediately
     // pre-resolve the proxy because it resides in the same scope as the
     // declaration.
-    Declare(name, mode, NULL, mode != VAR, CHECK_OK);
+    VariableProxy* proxy = Declare(name, mode, NULL, mode != VAR, CHECK_OK);
     nvars++;
     if (declaration_scope->num_var_or_const() > kMaxNumFunctionLocals) {
       ReportMessageAt(scanner().location(), "too_many_variables",
                       Vector<const char*>::empty());
       *ok = false;
       return NULL;
     }
 
     // Parse initialization expression if present and/or needed. A
     // declaration of the form:
@@ skipping 34 matching lines @@
       if (fni_ != NULL &&
           value->AsCall() == NULL &&
           value->AsCallNew() == NULL) {
         fni_->Infer();
       } else {
         fni_->RemoveLastFunction();
       }
       if (decl_props != NULL) *decl_props = kHasInitializers;
     }
 
+    // Record the end position of the initializer.
+    if (proxy->var() != NULL) {
+      proxy->var()->set_initializer_position(scanner().location().end_pos);
+    }
+
     // Make sure that 'const x' and 'let x' initialize 'x' to undefined.
     if (value == NULL && needs_init) {
       value = GetLiteralUndefined();
     }
 
     // Global variable declarations must be compiled in a specific
     // way. When the script containing the global variable declaration
     // is entered, the global variable must be declared, so that if it
     // doesn't exist (not even in a prototype of the global object) it
     // gets created with an initial undefined value. This is handled
@@ skipping 3577 matching lines @@
       result = parser.ParseProgram(source,
                                    info->is_global(),
                                    info->strict_mode_flag());
     }
   }
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal