Update dependency rollup to v2.50.4

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
rollup (source)	2.50.3 -> 2.50.4

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Release Notes

rollup/rollup

v2.50.4

Compare Source

2021-05-29

Bug Fixes

• Fix a situation where tree-shaking would stop including nodes prematurely (#​4111)
• Track mutations and accessor side effects when using __proto__ in an object literal (#​4112)
• Check for getter effects when spreading an object (#​4113)

Pull Requests

• #​4111: Always request a new tree-shaking pass when deoptimizations of a node are first included (@​lukastaegert)
• #​4112: Actually set the prototype when using a proto property (@​lukastaegert)
• #​4113: Track access side effects when using object spread operator (@​lukastaegert)

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