2.1.137 [ECMA-262/6] Section 25.4.4 Properties of the Promise Constructor

V0106: The Promise.length property is not configurable

The specification states:

 25.4.4 Properties of the Promise Constructor
  
     The value of the [[Prototype]] internal slot of the Promise constructor is the 
     intrinsic object %FunctionPrototype%.
  
     ... The Promise constructor has the following properties:

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The Promise.length property is not configurable.