Editorial: Change "non white space" to "non-|StrWhiteSpaceChar|" (tc3…

…9#1554)

... under "ToNumber Applied to the String Type".

The phrase "non-|StrWhiteSpaceChar|" skips both WhiteSpace
*and* LineTerminator code points, which is important
for an example like `Number("\n-0")`.

Also, insert "(if any)", because a StringNumericLiteral
might not have any such code point.

See tc39#1554 (comment)

spec.html

@@ -4523,7 +4523,7 @@ <h1>Runtime Semantics: MV</h1>
               The MV of <emu-grammar>StrUnsignedDecimalLiteral ::: DecimalDigits ExponentPart</emu-grammar> is the MV of |DecimalDigits| times 10<sup>_e_</sup>, where _e_ is the MV of |ExponentPart|.
             </li>
           </ul>
-          <p>Once the exact MV for a String numeric literal has been determined, it is then rounded to a value of the Number type. If the MV is 0, then the rounded value is *+0*<sub>𝔽</sub> unless the first non white space code point in the String numeric literal is `-`, in which case the rounded value is *-0*<sub>𝔽</sub>. Otherwise, the rounded value must be the Number value for the MV (in the sense defined in <emu-xref href="#sec-ecmascript-language-types-number-type"></emu-xref>), unless the literal includes a |StrUnsignedDecimalLiteral| and the literal has more than 20 significant digits, in which case the Number value may be either the Number value for the MV of a literal produced by replacing each significant digit after the 20th with a 0 digit or the Number value for the MV of a literal produced by replacing each significant digit after the 20th with a 0 digit and then incrementing the literal at the 20th digit position. A digit is significant if it is not part of an |ExponentPart| and</p>
+          <p>Once the exact MV for a String numeric literal has been determined, it is then rounded to a value of the Number type. If the MV is 0, then the rounded value is *+0*<sub>𝔽</sub> unless the first (if any) non-|StrWhiteSpaceChar| code point in the String numeric literal is `-`, in which case the rounded value is *-0*<sub>𝔽</sub>. Otherwise, the rounded value must be the Number value for the MV (in the sense defined in <emu-xref href="#sec-ecmascript-language-types-number-type"></emu-xref>), unless the literal includes a |StrUnsignedDecimalLiteral| and the literal has more than 20 significant digits, in which case the Number value may be either the Number value for the MV of a literal produced by replacing each significant digit after the 20th with a 0 digit or the Number value for the MV of a literal produced by replacing each significant digit after the 20th with a 0 digit and then incrementing the literal at the 20th digit position. A digit is significant if it is not part of an |ExponentPart| and</p>
           <ul>
             <li>
               it is not `0`; or