Update dependency webextension-polyfill to ^0.8.0

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
webextension-polyfill	^0.6.0 -> ^0.8.0

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Release Notes

mozilla/webextension-polyfill

v0.8.0

Compare Source

Bug Fixes

• browser.devtools.network.onRequestFinished is now wrapped by the polyfill and provides a promise-based request API object (#​250, fixes #​249)
• the promise wrappers has been updated to reject with Error instances (#​293, fixes #​257)

See all changes for 0.8.0

• https://unpkg.com/webextension-polyfill@0.8.0/dist/

v0.7.0

Compare Source

Features

• Added tabs.goBack and tabs.goForward (#​243)
• Added devtools.panels.elements.createSidebarPane to metadata (#​246)

See all changes for 0.7.0

• https://unpkg.com/webextension-polyfill@0.7.0/dist/

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