c009a18

Web Inspector: [SI] DOMManager rescans every DOM node for each pending frame document when splicing
https://bugs.webkit.org/show_bug.cgi?id=319454
rdar://182266167

Reviewed by NOBODY (OOPS!).

When a cross-origin frame document arrives before its owning iframe element is known,
it is queued and re-tried later. _trySpliceUnsplicedFrameDocuments() ran that retry by
calling _trySpliceFrameDocumentIntoNode() once per pending document, and each call
allocated a fresh Object.values(this._idToDOMNode) and linearly scanned every known DOM
node to find a matching iframe/frame element. It also constructed a new URL for the
frame document's URL on every candidate node. The result was O(pendingDocuments *
totalNodes) work with a per-document array allocation and redundant per-node URL parsing.

Collect the candidate iframe/frame elements once per pass in _unmatchedFrameNodes() and
reuse that list across all pending documents, and resolve the frame document's URL lazily
at most once per document. This lowers the cost to O(totalNodes + pendingDocuments *
frameElements) with no behavior change: an element matched by an earlier document in the
same pass is still skipped via its now-set contentDocument, so duplicate-URL documents and
already-populated iframes behave exactly as before.

Test: inspector/unit-tests/dom-frame-document-splice.html

* LayoutTests/inspector/unit-tests/dom-frame-document-splice-expected.txt: Added.
* LayoutTests/inspector/unit-tests/dom-frame-document-splice.html: Added.
* Source/WebInspectorUI/UserInterface/Controllers/DOMManager.js:
(WI.DOMManager.prototype._unmatchedFrameNodes):
(WI.DOMManager.prototype._trySpliceFrameDocumentIntoNode):
(WI.DOMManager.prototype._trySpliceUnsplicedFrameDocuments):

c009a18

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