fix(runner): remove explicit error on all tests failed

- there are failOnFailingTestSuite and failOnEmptyTestSuite, so in this there is no neccesity

Fixes karma-runner#3367

Author: ilgonmic

lib/browser.js

@@ -87,10 +87,6 @@ class Browser {
       this.setState(CONNECTED)
       this.lastResult.totalTimeEnd()
 
-      if (!this.lastResult.success) {
-        this.lastResult.error = true
-      }
-
       this.emitter.emit('browsers_change', this.collection)
       this.emitter.emit('browser_complete', this, result)