Regenerate overridden members

[theKashey]

During HOT stand-in compares the old class and the new one.
It created 2 instances and checking what was changed in class creation.
If something did - it will inject changed value into the real instances. Thus the arrow function update work.

But, in case of ES6 RHL could not change the constructor, as a result it always compares the "first" version and the last one. Thus - it will not inject "not changed" method.... keeping the previously injected variant.

This PR just fixes this moment, and checking also injected values, and fixes #836

[codecov-io]

Codecov Report

Merging #837 into next will not change coverage.
The diff coverage is n/a.

@@         Coverage Diff         @@
##           next   #837   +/-   ##
===================================
  Coverage    85%    85%           
===================================
  Files        23     23           
  Lines       507    507           
  Branches    144    139    -5     
===================================
  Hits        431    431           
- Misses       56     63    +7     
+ Partials     20     13    -7

Impacted Files	Coverage Δ
packages/react-hot-loader/src/global/modules.js	74.19% <0%> (ø)	⬆️
...ot-loader/src/internal/stack/hydrateLegacyStack.js	8.69% <0%> (ø)	⬆️

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