CLI: Fix TAP compliance for early errors (e.g. syntax error in test file)

Cherry-picked from 62ca15a (3.0.0-dev).
> Core: Convert "No tests were run." from fake test to error

Early errors produced output like so:

```
not ok 1 global failure
  ---
  message: ReferenceError: boom is not defined
  stack: |
    ReferenceError: boom is not defined
        at /example.test.js
  ...
Bail out! ReferenceError: boom is not defined
TAP version 13
1..1
```

Instead of:

```
TAP version 13
not ok 1 global failure
  ---
  message: ReferenceError: boom is not defined
  stack: |
    ReferenceError: boom is not defined
        at /example.test.js
  ...
Bail out! ReferenceError: boom is not defined
1..1
```

Because prior to the introduction of the "error" event in 2.17.0,
the only failures were test failures, and those would not begin until
after QUnit.begin() / "runStart" event.

Author: Krinkle

src/reporters/TapReporter.js

@@ -183,6 +183,7 @@ export default class TapReporter {
     this.log = options.log || Function.prototype.bind.call(console.log, console);
 
     this.testCount = 0;
+    this.started = false;
     this.ended = false;
     this.bailed = false;
 
@@ -197,7 +198,10 @@ export default class TapReporter {
   }
 
   onRunStart (_runSuite) {
-    this.log('TAP version 13');
+    if (!this.started) {
+      this.log('TAP version 13');
+      this.started = true;
+    }
   }
 
   onError (error) {
@@ -210,6 +214,7 @@ export default class TapReporter {
     // Imitate onTestEnd
     // Skip this if we're past "runEnd" as it would look odd
     if (!this.ended) {
+      this.onRunStart();
       this.testCount = this.testCount + 1;
       this.log(`not ok ${this.testCount} ${kleur.red('global failure')}`);
       this.logError(error);

test/cli/TapReporter.js

@@ -36,6 +36,9 @@ QUnit.module('TapReporter', hooks => {
 
   hooks.beforeEach(function () {
     emitter = new EventEmitter();
+    emitter.clear = function () {
+      buffer = '';
+    };
     last = undefined;
     buffer = '';
     QUnit.reporters.tap.init(emitter, {
@@ -146,6 +149,9 @@ QUnit.module('TapReporter', hooks => {
   });
 
   QUnit.test('output global failure (string)', assert => {
+    emitter.emit('runStart');
+    emitter.clear();
+
     emitter.emit('error', 'Boo');
 
     assert.strictEqual(buffer, 'not ok 1 ' + kleur.red('global failure') + `
@@ -159,6 +165,9 @@ Bail out! Boo
   });
 
   QUnit.test('output global failure (Error)', assert => {
+    emitter.emit('runStart');
+    emitter.clear();
+
     const err = new ReferenceError('Boo is not defined');
     mockStack(err);
     emitter.emit('error', err);

test/cli/fixtures/syntax-error.tap.txt

@@ -1,6 +1,7 @@
 # name: load file with syntax error
 # command: ["qunit", "syntax-error.js"]
 
+TAP version 13
 not ok 1 global failure
   ---
   message: |+
@@ -13,7 +14,6 @@ not ok 1 global failure
         at internal
   ...
 Bail out! Error: Failed to load file syntax-error.js
-TAP version 13
 not ok 2 global failure
   ---
   message: No tests were run.

test/cli/fixtures/unhandled-rejection.tap.txt

@@ -1,6 +1,7 @@
 # name: unhandled rejection
 # command: ["qunit","unhandled-rejection.js"]
 
+TAP version 13
 not ok 1 global failure
   ---
   message: Error: outside of a test context
@@ -13,15 +14,13 @@ not ok 1 global failure
         at internal
   ...
 Bail out! Error: outside of a test context
-TAP version 13
 not ok 2 Unhandled Rejections > test passes just fine, but has a rejected promise
   ---
   message: global failure: Error: Error thrown in non-returned promise!
   severity: failed
   stack: |
     Error: Error thrown in non-returned promise!
         at /qunit/test/cli/fixtures/unhandled-rejection.js:10:13
-        at internal
   ...
 1..2
 # pass 0