Fix inspector-protocol/stylesheet-tracking-restart.js

The test became flaky because it was relying on the order in which
stylesheets are created on the backend. This CL changes the test to
rely on sourceURL instead of stylesheetId (incremental) to make the
test not flaky. Drive-by: adds .cache created by clangd to .gitignore

Fixed: 1104288
Change-Id: I243d97018c2153d228f78e07bd55b625265ec8da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2299219Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Alex Rudenko <alexrudenko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#788538}

.gitignore

@@ -324,5 +324,8 @@ vs-chromium-project.txt
 # Ignore IntelliJ files.
 .idea/
 
+# Ignore cache folder created by clangd
+.cache
+
 # Ignore the default results output directory for tools/run-swarmed.py
 /results

third_party/blink/web_tests/TestExpectations

@@ -6858,7 +6858,6 @@ crbug.com/1104333 http/tests/devtools/bindings/inline-styles-binding.js [ Pass F
 crbug.com/1104910 [ Mac ] external/wpt/webaudio/the-audio-api/the-oscillatornode-interface/osc-basic-waveform.html [ Pass Failure ]
 crbug.com/1104910 fast/dom/cssTarget-crash.html [ Pass Timeout Failure ]
 crbug.com/1104910 fast/peerconnection/RTCPeerConnection-reload-interesting-usage.html [ Pass Failure ]
-crbug.com/1104910 inspector-protocol/stylesheet-tracking-restart.js [ Pass Failure ]
 crbug.com/1104910 [ Win ] virtual/cache-storage-eager-reading/external/wpt/service-workers/service-worker/registration-updateviacache.https.html [ Pass Failure ]
 crbug.com/1104910 [ Win ] http/tests/devtools/elements/styles-1/dynamic-style-tag.js [ Pass Failure ]
 crbug.com/1104910 [ Mac10.15 ] editing/selection/selection-background.html [ Pass Failure ]

third_party/blink/web_tests/inspector-protocol/stylesheet-tracking-restart-expected.txt

@@ -3,8 +3,8 @@ This test checks that if style sheet is removed between two inspector launches i
 Running test
 Opening front-end for the first time
 Enabling CSS domain.
- - style sheet added: foo.css
  - style sheet added: bar.css
+ - style sheet added: foo.css
 Closing inspector.
 
 Removing style sheet.

third_party/blink/web_tests/inspector-protocol/stylesheet-tracking-restart.js

@@ -36,7 +36,7 @@
     session.protocol.DOM.enable();
     await session.protocol.CSS.enable();
     var headers = {};
-    headersAdded.sort((a, b) => a.styleSheetId - b.styleSheetId);
+    headersAdded.sort((a, b) => a.sourceURL.localeCompare(b.sourceURL));
     for (var header of headersAdded) {
       headers[header.styleSheetId] = header.sourceURL;
       testRunner.log(' - style sheet added: ' + header.sourceURL);