[Menu] Convert to function component

[joshwooding]

• I have followed (at least) the PR section of the contributing guide.

[joshwooding]

I'm expecting the last three tests to fail.

• should call props.onEntering with element if exists
  • I already check something is passed to onEntering in the handler tests
• should call props.onEntering, disableAutoFocusItem
  • I can check something is passed to onEntering but I'm unsure why disabledAutoFocusItem would affect onEntering
• call handleListKeyDown without onClose prop
  • No idea how to test this one, do we need to?

@oliviertassinari ?

[mui-pr-bot]

@material-ui/core: parsed: -0.24% 😍, gzip: -0.04% 😍

Details of bundle changes.

Comparing: b3e4c49...be54b64

bundle	parsed diff	gzip diff	prev parsed	current parsed	prev gzip	current gzip
@material-ui/core	-0.24%	-0.04%	349,795	348,943	90,100	90,065
@material-ui/core/Paper	-0.00%	-0.05%	67,869	67,866	19,832	19,822
@material-ui/core/Paper.esm	-0.00%	-0.02%	60,201	60,198	18,572	18,568
@material-ui/core/Popper	+0.01% 🔺	-0.02%	30,460	30,463	10,528	10,526
@material-ui/core/styles/createMuiTheme	0.00%	0.00%	17,384	17,384	5,726	5,726
@material-ui/core/useMediaQuery	0.00%	0.00%	2,469	2,469	1,043	1,043
@material-ui/lab	+0.01% 🔺	-0.02%	148,712	148,720	43,698	43,691
@material-ui/styles	-0.01%	-0.06%	53,102	53,099	15,444	15,435
@material-ui/system	0.00%	0.00%	17,136	17,136	4,527	4,527
Button	-0.00%	-0.01%	88,356	88,355	26,177	26,175
Modal	0.00%	-0.00%	82,460	82,461	24,670	24,669
colorManipulator	0.00%	0.00%	3,232	3,232	1,299	1,299
docs.landing	0.00%	0.00%	49,958	49,958	10,837	10,837
docs.main	-0.14%	-0.01%	646,389	645,467	200,783	200,756
packages/material-ui/build/umd/material-ui.production.min.js	-0.26%	-0.09%	298,354	297,587	82,635	82,559

Generated by 🚫 dangerJS against be54b64

[oliviertassinari]

@ryancogswell I hope this change doesn't conflict with your effort. Let us know.

[oliviertassinari]

@joshwooding I have given a shot to the problem. I have removed the did mount logic. It works great without. I have removed the .instance() usage in the tests.

[ryancogswell]

I hope this change doesn't conflict with your effort. Let us know.

@oliviertassinari So far, my work has only been in MenuList and its tests, but I will be working in Menu and its tests soon. As long as this is merged soon it won’t cause me any issues.