Don't reload functional properties

[theKashey]

revert #949, fixes #995, #978, #969, #984

Implements #1001

Also fixes #969 with "this5", as long I've got _this9, and now using regexp to get the "right" _this[\d] from the code.

[codecov-io]

Codecov Report

Merging #1002 into master will increase coverage by 1.11%.
The diff coverage is 80%.

@@            Coverage Diff             @@
##           master    #1002      +/-   ##
==========================================
+ Coverage   86.51%   87.62%   +1.11%     
==========================================
  Files          31       31              
  Lines         816      962     +146     
  Branches      192      254      +62     
==========================================
+ Hits          706      843     +137     
- Misses         91      101      +10     
+ Partials       19       18       -1

Impacted Files	Coverage Δ
src/proxy/inject.js	77.58% <80%> (-0.2%)	⬇️
src/reconciler/proxies.js	100% <0%> (ø)	⬆️
src/reactHotLoader.js	96.22% <0%> (+2.28%)	⬆️
src/reconciler/hotReplacementRender.js	86% <0%> (+3.8%)	⬆️

---

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 e7d7577...5bfd8cf. Read the comment docs.