[workspace] Replace one more usage of IgnoreListManager.instance()

R=nvitkov@chromium.org

Bug: 458180550
Change-Id: I6efa46cbeb33f6d0ac5b7ba054119be4cea8ad03
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7165022
Reviewed-by: Nikolay Vitkov <nvitkov@chromium.org>
Auto-Submit: Simon Zünd <szuend@chromium.org>
Commit-Queue: Nikolay Vitkov <nvitkov@chromium.org>

Author: szuend

front_end/models/workspace/IgnoreListManager.ts

@@ -257,8 +257,7 @@ export class IgnoreListManager extends Common.ObjectWrapper.ObjectWrapper<EventT
   private async updateScriptRanges(script: SDK.Script.Script, sourceMap: SDK.SourceMap.SourceMap|undefined):
       Promise<void> {
     let hasIgnoreListedMappings = false;
-    if (!IgnoreListManager.instance().isUserIgnoreListedURL(
-            script.sourceURL, {isContentScript: script.isContentScript()})) {
+    if (!this.isUserIgnoreListedURL(script.sourceURL, {isContentScript: script.isContentScript()})) {
       hasIgnoreListedMappings =
           sourceMap?.sourceURLs().some(
               url => this.isUserIgnoreListedURL(url, {isKnownThirdParty: sourceMap.hasIgnoreListHint(url)})) ??