Check for React presence when detecting WEBPACK_REACT type

[Hypnosphi]

To prevent incorrect detection when a vue project has webpack installed

[Hypnosphi]

We should probably extract those checks into a function

[codecov]

Codecov Report

Merging #1646 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #1646   +/-   ##
=======================================
  Coverage   20.87%   20.87%           
=======================================
  Files         251      251           
  Lines        5629     5629           
  Branches      675      690   +15     
=======================================
  Hits         1175     1175           
+ Misses       3952     3926   -26     
- Partials      502      528   +26

Impacted Files	Coverage Δ
lib/cli/lib/detect.js	0% <0%> (ø)	⬆️
addons/knobs/src/components/PropField.js	10.86% <0%> (ø)	⬆️
lib/ui/src/modules/ui/containers/layout.js	12.5% <0%> (ø)	⬆️
...es__/update-addon-info/update-addon-info.output.js	0% <0%> (ø)	⬆️
addons/info/src/components/Props.js	37.2% <0%> (ø)	⬆️
lib/ui/src/modules/ui/libs/filters.js	53.33% <0%> (ø)	⬆️
app/react-native/src/bin/storybook-start.js	0% <0%> (ø)	⬆️
...ponents/left_panel/stories_tree/tree_decorators.js	32.29% <0%> (ø)	⬆️
addons/knobs/src/components/types/Number.js	8.06% <0%> (ø)	⬆️
addons/info/src/components/PropTable.js	20.16% <0%> (ø)	⬆️
... and 18 more

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[ndelangen]

Merge when ready