Add State Manager API tests to karma

[ryanio]

This PR:

1. Adds tests/api/state/stateManager.js back to karma.
2. Skips slow test when running in karma: should generate the genesis state root correctly for mainnet
3. Modifies test should generate correct genesis state root for all chains to should generate the genesis state root correctly for all other chains (since mainnet is already tested prior).
4. Runs karma in both headless Firefox and Chrome for increased browser coverage.
5. Removes unneeded karma-detect-browsers.

Closes #465

[ryanio]

Sorry about the prettified files, the diffs are a bit hard to read/parse.

[codecov]

Codecov Report

Merging #653 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master    #653   +/-   ##
======================================
  Coverage    91.4%   91.4%           
======================================
  Files          31      31           
  Lines        1978    1978           
  Branches      326     326           
======================================
  Hits         1808    1808           
  Misses         90      90           
  Partials       80      80

Flag	Coverage Δ
#vm	91.4% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f363377...1dd35f6. Read the comment docs.

[evertonfraga]

That's great, @ryanio.

I have only one suggestion, which is to extract the expression typeof window !== 'undefined' && window.__karma__ to a function in util.js.

Not that we want to reuse that much around, but just to give this logic a proper name.

[evertonfraga]

👍

[evertonfraga]

Logic was extracted to isRunningInKarma().

[evertonfraga]

👍

[holgerd77]

Yes, can confirm that this is hard to read/review 😛, next time stuff like this should better be two subsequent PRs, otherwise the structural risk to overlook something is unnecessarily increased.

Otherwise looks good. Won't merge myself, not sure if this intervenes somehow with the monorepo process or something, but otherwise @evertonfraga or @ryanio feel free to merge.

This is increased browser (type) coverage is also cool, browser compatibility gets historically somewhat too little attention within EthereumJS.

[ryanio]

Thanks, sounds good. In the future if a file isn't prettified I'll leave it out so the diff is cleaner and run the prettify in a separate PR.