Do not report error for test failures

Test failures are not an exceptional event. By reporting them as though
they are exceptional, test262-harness forces consumers to ignore the
status code. This makes it difficult to detect true operational errors,
e.g. when the interpreter under test crashes, since they are
indistinguishable from test failures.

Consumers who wish to react to test failures should do so by parsing the
tool's output.

bin/run.js

@@ -178,9 +178,6 @@ const results = zip(pool, tests).pipe(
 );
 
 const emitter = new ResultsEmitter(results);
-emitter.on('fail', function () {
-  process.exitCode = 1;
-});
 reporter(emitter, reporterOpts);
 
 function printVersion() {

test/test.js

@@ -36,7 +36,6 @@ const tests = [
       '--includesDir', './test/test-includes',
       './test/collateral/test/**/*.js',
     ],
-    { exitCode: 1 },
   ],
   [
     [
@@ -48,7 +47,7 @@ const tests = [
       '--includesDir', './test-includes',
       'collateral/test/**/*.js',
     ],
-    { cwd: 'test', exitCode: 1 },
+    { cwd: 'test' },
   ],
   [
     [
@@ -117,7 +116,6 @@ const tests = [
       '--reporter-keys', 'attrs,result,rawResult',
       './test/collateral-preprocessor/test/autofail.js',
     ],
-    { exitCode: 1 },
   ],
 ].reduce((accum, a) => {
   let b = a.slice();