clang-tidy: loop variable is copied but only used as const reference in Document.cpp, Element.cpp

[David Kilzer (:ddkilzer)]

Running `clang-tidy '-checks=-*,performance-for-range-copy' ...` on Document.cpp and Element.cpp finds these unnecessary copies:

Source/WebCore/dom/Document.cpp:7907:15: warning: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy]
    for (auto observer : m_intersectionObserversWithPendingNotifications) {
              ^
         const  &

Source/WebCore/dom/Element.cpp:1777:19: warning: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy]
        for (auto observer : observerData->observers) {
                  ^
             const  &
Source/WebCore/dom/Element.cpp:3399:15: warning: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy]
    for (auto observer : observerData->observers)
              ^
         const  &

[Radar WebKit Bug Importer]

<rdar://problem/46694035>

[David Kilzer (:ddkilzer)]

Created attachment 357226 [details]
Patch v1

[WebKit Commit Bot]

Comment on attachment 357226 [details]
Patch v1

Clearing flags on attachment: 357226

Committed r239160: <https://trac.webkit.org/changeset/239160>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.