Chore: dogfooding no-var rule and remove vars (refs #6407)

[mysticatea]

Refs #6407.

This PR applies no-var rule to our code.

• I tweaked some code for references from outside of the block which has declarations.
• I fixed some tests which are using our .eslintrc.yml or our code with --no-eslintrc.

  • eslint/tests/lib/cli-engine.js

    Line 103 in e825458

    it("should report one message when using local cwd .eslintrc", function() {

  • eslint/tests/lib/cli-engine.js

    Line 425 in e825458

    it("should report zero messages when given a config file and a valid file and espree as parser", function() {

  • eslint/tests/lib/cli-engine.js

    Line 2258 in e825458

    it("should report 4 error messages when looking for errors only", function() {

• I added a dependency karma-babel-preprocessor for tests of PhantomJS. let in tests/lib/eslint.js caused syntax errors.

[eslintbot]

LGTM

[mysticatea]

Also, let is slower than var, so I profiled performance between before/after this PR. As a result, I could see no significant differences.

Before

C:\Users\t-nagashima.AD\Documents\GitHub\eslint [chore/no-var-and-prefer-const]> npm run perf

> eslint@3.1.1 perf C:\Users\t-nagashima.AD\Documents\GitHub\eslint
> node Makefile.js perf


Loading:
  Load performance Run #1:  363.21531ms
  Load performance Run #2:  359.273145ms
  Load performance Run #3:  361.171179ms
  Load performance Run #4:  366.161369ms
  Load performance Run #5:  363.397929ms

  Load Performance median:  363.21531ms


Single File:
  CPU Speed is 3392 with multiplier 13000000
  Performance Run #1:  3858.823388ms
  Performance Run #2:  3873.5548909999998ms
  Performance Run #3:  3858.693893ms
  Performance Run #4:  3937.017115ms
  Performance Run #5:  3874.006157ms

  Performance budget exceeded: 3873.5548909999998ms (limit: 3832.5471698113206ms)


Multi Files (450 files):
  CPU Speed is 3392 with multiplier 39000000
  Performance Run #1:  14332.274141ms
  Performance Run #2:  12398.347067ms
  Performance Run #3:  11891.07006ms
  Performance Run #4:  11816.343988ms
  Performance Run #5:  12031.848532ms

  Performance budget exceeded: 12031.848532ms (limit: 11497.641509433963ms)

After

C:\Users\t-nagashima.AD\Documents\GitHub\eslint [chore/no-var-and-prefer-const +0 ~519 -0 !]> npm run perf

> eslint@3.1.1 perf C:\Users\t-nagashima.AD\Documents\GitHub\eslint
> node Makefile.js perf


Loading:
  Load performance Run #1:  361.830118ms
  Load performance Run #2:  360.144889ms
  Load performance Run #3:  363.776148ms
  Load performance Run #4:  355.25944ms
  Load performance Run #5:  363.504784ms

  Load Performance median:  361.830118ms


Single File:
  CPU Speed is 3392 with multiplier 13000000
  Performance Run #1:  3892.6454169999997ms
  Performance Run #2:  3874.342117ms
  Performance Run #3:  3895.069274ms
  Performance Run #4:  3918.40291ms
  Performance Run #5:  3852.414501ms

  Performance budget exceeded: 3892.6454169999997ms (limit: 3832.5471698113206ms)


Multi Files (450 files):
  CPU Speed is 3392 with multiplier 39000000
  Performance Run #1:  11876.235927ms
  Performance Run #2:  11997.202451ms
  Performance Run #3:  11880.865707ms
  Performance Run #4:  11883.21531ms
  Performance Run #5:  11817.850825ms

  Performance budget exceeded: 11880.865707ms (limit: 11497.641509433963ms)

[gyandeeps]

LGTM, waiting for others to review.

[platinumazure]

LGTM with merge-base of 1025772. I can't speak to the karma preprocessor though, hopefully someone else can cover that.

This is one of those things that should probably be merged quickly; otherwise, @mysticatea will either need to rebase with some frequency or scramble with another commit after this is merged, if someone has added a var statement in the meanwhile.

[ilyavolodin]

LGTM