make the BOM visible in the test output

src/harness/compilerRunner.ts

@@ -119,7 +119,7 @@ class CompilerBaselineRunner extends RunnerBase {
             });
 
             function getByteOrderMarkText(file: Harness.Compiler.GeneratedFile): string {
-                return file.writeByteOrderMark ? String.fromCharCode(ts.CharacterCodes.byteOrderMark) : '';
+                return file.writeByteOrderMark ? "\u00EF\u00BB\u00BF" : "";
             }
 
             function getErrorBaseline(toBeCompiled: { unitName: string; content: string }[],

tests/baselines/reference/generateBOM.js

@@ -4,8 +4,8 @@
 var x;
 
 //// [generateBOM.js]
-var x;
+var x;
 //# sourceMappingURL=generateBOM.js.map
 
 //// [generateBOM.d.ts]
-declare var x: any;
+declare var x: any;