Editorial: Remove unused steps from definitions of Contains (#1519)

... specifically, steps of the form:
  If _symbol_ is an |Identifier| and StringValue of _symbol_
  is the same value as the StringValue of |IdentifierName|,
  return *true*.

Resolves issue #831.

As @allenwb points out, the intended use case for such steps
does not occur in the spec.

And as I point out, these steps are semantically problematic.

If the intended use case ever *does* occur,
I'm guessing we'll find a different way to handle it.

spec.html

@@ -12793,7 +12793,6 @@ <h1>Static Semantics: Contains</h1>
         <emu-grammar>LiteralPropertyName : IdentifierName</emu-grammar>
         <emu-alg>
           1. If _symbol_ is a |ReservedWord|, return *false*.
-          1. If _symbol_ is an |Identifier| and StringValue of _symbol_ is the same value as the StringValue of |IdentifierName|, return *true*.
           1. Return *false*.
         </emu-alg>
       </emu-clause>
@@ -13473,21 +13472,18 @@ <h1>Static Semantics: Contains</h1>
         <emu-alg>
           1. If |MemberExpression| Contains _symbol_ is *true*, return *true*.
           1. If _symbol_ is a |ReservedWord|, return *false*.
-          1. If _symbol_ is an |Identifier| and StringValue of _symbol_ is the same value as the StringValue of |IdentifierName|, return *true*.
           1. Return *false*.
         </emu-alg>
         <emu-grammar>SuperProperty : `super` `.` IdentifierName</emu-grammar>
         <emu-alg>
           1. If _symbol_ is the |ReservedWord| `super`, return *true*.
           1. If _symbol_ is a |ReservedWord|, return *false*.
-          1. If _symbol_ is an |Identifier| and StringValue of _symbol_ is the same value as the StringValue of |IdentifierName|, return *true*.
           1. Return *false*.
         </emu-alg>
         <emu-grammar>CallExpression : CallExpression `.` IdentifierName</emu-grammar>
         <emu-alg>
           1. If |CallExpression| Contains _symbol_ is *true*, return *true*.
           1. If _symbol_ is a |ReservedWord|, return *false*.
-          1. If _symbol_ is an |Identifier| and StringValue of _symbol_ is the same value as the StringValue of |IdentifierName|, return *true*.
           1. Return *false*.
         </emu-alg>
         <emu-grammar>OptionalChain : `?.` IdentifierName</emu-grammar>