2.1.9 [ECMA-262/6] Section 9.4.4.5 [[Delete]] (P)

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V0038: [[Delete]] removes the property even if the configurable property is false

The specification states:

 9.4.4.5 [[Delete]] (P)
  
     The [[Delete]] internal method of an arguments exotic object when called with a 
     property key P performs the following steps:
  
         1.  Let map be the value of the [[ParameterMap]] internal slot of the arguments 
             object.
         2.  Let isMapped be HasOwnProperty(map, P).
         3.  Assert: isMapped is not an abrupt completion.
         4.  Let result be the result of calling the default [[Delete]] internal method 
             for ordinary objects (9.1.10) on the arguments object passing P as the 
             argument.
         5.  ReturnIfAbrupt(result).
         6.  If result is true and the value of isMapped is true, then
             a. Call map.[[Delete]](P).
         7.  Return result.

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In step 4, the [[Delete]] internal method removes the property even if the configurable property is false.