Editorial: Delete "the Number value for" in Number::leftShift (tc39#2273

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For consistency with Number::signedRightShift and Number::unsignedRightShift, the result of a left or right shift is a Number, so it doesn't make sense to get "the Number value for" that result.

spec.html

@@ -1762,7 +1762,7 @@ <h1>Number::leftShift ( _x_, _y_ )</h1>
             1. Let _lnum_ be ! ToInt32(_x_).
             1. Let _rnum_ be ! ToUint32(_y_).
             1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
-            1. Return the Number value for the result of left shifting _lnum_ by _shiftCount_ bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+            1. Return the result of left shifting _lnum_ by _shiftCount_ bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
           </emu-alg>
         </emu-clause>