fix(test): karma-dist should test bundle under dist

[JiaLiPassion]

update karma-dist.conf.js

current karma-dist.conf.js will load bundles under dist and the purpose is to test those built bundles instead of the dev version which under build folder.
so in karma-dist.conf.js, we will load

 config.files.push('dist/zone.js');
 config.files.push('dist/async-test.js');
...

But in current test cases will load some of the lib directly from build folder, for example in async-test.spec.ts, in current version, it will load

import '../../lib/zone-spec/async-test';

so the test case in fact will not test the bundle under dist but build.

---

in this PR, I load all needed bundles in karma-dist.conf.js and remove all directly import from test specs. And also modify the test entry classes to make sure currently test cases will be ok for both build test and dist test.

• in dev mode, test bundles under build.
• in dist mode, test bundles under dist.

Also disable ios 8.4 test because saucelabs seems not stable

change default karma browser to Chrome.

change rollup globals.

add ios 11, edge 15, android 7.1 to ci test.

[mhevery]

can you resolve these?