babel-types: avoid recreating validator closures

[jridgewell]

Q	A
Patch: Bug Fix?	No
Major: Breaking Change?	No
Minor: New Feature?	No
Deprecations?	No
Spec Compliancy?	No
Tests Added/Pass?	No
Fixed Tickets
License	MIT
Doc PR
Dependency Changes

MemberExpression, ObjectMethod, and ObjectProperty, and ClassMethod's property validators recreated their validating closure every time.

[mention-bot]

@jridgewell, thanks for your PR! By analyzing the history of the files in this pull request, we identified @existentialism, @hzoo and @phantom10111 to be potential reviewers.

[codecov]

Codecov Report

Merging #5821 into 7.0 will decrease coverage by <.01%.
The diff coverage is 91.66%.

@@            Coverage Diff            @@
##              7.0   #5821      +/-   ##
=========================================
- Coverage   84.91%   84.9%   -0.01%     
=========================================
  Files         284     284              
  Lines        9930    9946      +16     
  Branches     2788    2788              
=========================================
+ Hits         8432    8445      +13     
- Misses        988     991       +3     
  Partials      510     510

Impacted Files	Coverage Δ
packages/babel-types/src/definitions/es2015.js	96.66% <83.33%> (+0.51%)	⬆️
packages/babel-types/src/definitions/core.js	98.52% <94.44%> (+0.31%)	⬆️
packages/babel-helper-call-delegate/src/index.js	64% <0%> (-4%)	⬇️
packages/babel-traverse/src/path/modification.js	72.11% <0%> (-0.97%)	⬇️
packages/babel-traverse/src/path/context.js	85.34% <0%> (-0.87%)	⬇️

---

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 1e55653...eaaa09e. Read the comment docs.

[hzoo]

Probably unnecessary but we could just hoist and reuse assertNodeType("Expression") everywhere right? Or just precompute everything (I guess that's what prepack would do).

I was joking a while ago we could do a babel-plugin that computes things like t.isFunctionExpression() -> node.type === 'FunctionExpression'

[hzoo]

Should probably measure all that stuff though (and would also cause more bugs)