Ensure that the entire contents are simply 'use strict'.

src/compiler/emitter.ts

@@ -7636,7 +7636,7 @@ const _super = (function (geti, seti) {
             }
 
             function isUseStrictPrologue(node: ExpressionStatement): boolean {
-                return !!(node.expression as StringLiteral).text.match(/use strict/);
+                return (node.expression as StringLiteral).text === "use strict";
             }
 
             function ensureUseStrictPrologue(startWithNewLine: boolean, writeUseStrict: boolean) {