2.1.32 [ECMA-262/6] Section 13.7.4.7 Runtime Semantics: LabelledEvaluation

V0127: For loops don't get per-iteration environments for let variable declarations

The specification states:

 13.7.4.7 Runtime Semantics: LabelledEvaluation
  
     With argument labelSet.
  
     See also: 13.1.7, 13.7.2.6, 13.7.3.6, 13.7.5.11, 13.13.14.
     ...
     IterationStatement : for ( LexicalDeclaration Expressionopt ; Expressionopt ) 
     Statement
         ...
         9.  If isConst is false, let perIterationLets be boundNames otherwise let 
             perIterationLets be « ».
         ...

IE11 Mode (All versions)

In step 9, perIterationLets is in effect « » regardless of the value of isConst. As a result, for loops don't get per-iteration environments for let variable declarations.