Fix easy misunderstanding "! ===" (microsoft#37838)

* Remove unnecessary Non-null assertion operator

* Wrap Non-null assertion operator inside parentheses

Author: zhangciwu

src/compiler/scanner.ts

@@ -307,14 +307,14 @@ namespace ts {
     /* @internal */ export function isUnicodeIdentifierStart(code: number, languageVersion: ScriptTarget | undefined) {
         return languageVersion! >= ScriptTarget.ES2015 ?
             lookupInUnicodeMap(code, unicodeESNextIdentifierStart) :
-            languageVersion! === ScriptTarget.ES5 ? lookupInUnicodeMap(code, unicodeES5IdentifierStart) :
+            languageVersion === ScriptTarget.ES5 ? lookupInUnicodeMap(code, unicodeES5IdentifierStart) :
                 lookupInUnicodeMap(code, unicodeES3IdentifierStart);
     }
 
     function isUnicodeIdentifierPart(code: number, languageVersion: ScriptTarget | undefined) {
         return languageVersion! >= ScriptTarget.ES2015 ?
             lookupInUnicodeMap(code, unicodeESNextIdentifierPart) :
-            languageVersion! === ScriptTarget.ES5 ? lookupInUnicodeMap(code, unicodeES5IdentifierPart) :
+            languageVersion === ScriptTarget.ES5 ? lookupInUnicodeMap(code, unicodeES5IdentifierPart) :
                 lookupInUnicodeMap(code, unicodeES3IdentifierPart);
     }
 

src/services/codefixes/addMissingAwait.ts

@@ -211,7 +211,7 @@ namespace ts.codefix {
             reference;
         const diagnostic = find(diagnostics, diagnostic =>
             diagnostic.start === errorNode.getStart(sourceFile) &&
-            diagnostic.start + diagnostic.length! === errorNode.getEnd());
+            (diagnostic.start + diagnostic.length!) === errorNode.getEnd());
 
         return diagnostic && contains(errorCodes, diagnostic.code) ||
             // A Promise is usually not correct in a binary expression (it’s not valid