Removed unused imports

[perlun]

• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes fix #11185
• These changes do not require tests because it only removes dead code.

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This fixes #11185.

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This change is

[highfive]

Heads up! This PR modifies the following files:

• @bholley: components/style/stylesheets.rs, components/style/properties/properties.mako.rs, components/style/viewport.rs, components/style/selector_matching.rs, components/style/media_queries.rs, components/style/font_face.rs
• @fitzgen: components/profile/mem.rs
• @KiChjang: components/script/dom/textdecoder.rs, components/script/dom/textencoder.rs, components/script/dom/htmlscriptelement.rs, components/script/dom/htmlcanvaselement.rs, components/script/dom/servohtmlparser.rs, components/script/dom/blob.rs, components/script/dom/window.rs, components/script/dom/document.rs, components/script/dom/domquad.rs, components/script/dom/cssstyledeclaration.rs, components/script/task_source/user_interaction.rs, components/script/dom/dedicatedworkerglobalscope.rs, components/script/dom/element.rs, components/script/dom/htmlfieldsetelement.rs, components/script/dom/htmlformcontrolscollection.rs, components/script/dom/xmlhttprequest.rs, components/net_traits/lib.rs, components/net_traits/lib.rs, components/script/dom/bindings/weakref.rs, components/script/dom/htmlbodyelement.rs, components/script/dom/htmlmediaelement.rs, components/script/dom/htmltextareaelement.rs, components/script/dom/worker.rs, components/script/parse/xml.rs, components/script/dom/errorevent.rs, components/net_traits/image/base.rs, components/net_traits/image/base.rs, components/net/cookie_storage.rs, components/script/dom/htmlimageelement.rs, components/script/dom/htmlinputelement.rs, components/script/timers.rs, components/script/dom/htmliframeelement.rs, components/script/dom/htmlareaelement.rs, components/script/dom/htmlbuttonelement.rs, components/script/dom/node.rs, components/script/dom/canvasrenderingcontext2d.rs, components/script/dom/keyboardevent.rs, components/script/dom/xmldocument.rs, components/script/dom/htmlformelement.rs, components/script/dom/storage.rs, components/script/dom/websocket.rs, components/script/dom/closeevent.rs, components/script/dom/htmlelement.rs, components/script/dom/formdata.rs

[highfive]

Warning

• These commits modify gfx, style, layout, net, and script code, but no tests are modified. Please consider adding a test!

[Manishearth]

@bors-servo r+

[bors-servo]

📌 Commit 2f7ed1d has been approved by Manishearth

[bors-servo]

⌛ Testing commit 2f7ed1d with merge 2c674d0...

[bors-servo]

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel, mac-dev-unit, mac-rel-css, mac-rel-wpt, windows