Ensure we don't end up in an infinite loop when updating path.

1. Don't call handleValueChange if gr-drop-down-list hasn't actually changed value

Analysis:
 - Navigate to https://go-review.googlesource.com/c/go/+/494187/29/src/runtime/trace2buf.go
 - gr-diff-view eventually ends up with this.path = src/runtime/trace2buf.go.
 - Press Shift+m
 - handleNextUnreviewedFile gets called
 - this.setReviewed(true) gets called
 - this.navigateToUnreviewedFile('next')
 - this.naveToFile gets called which computes newPath src/runtime/trace2cpu.go
 - this.getChangeModel().navigateToDiff gets called wit the newPath
 - Before the model has time to finish updating gr-diff-view, the header gets re-rerendered due to this.setReviewed(true)
 - this.path gets updated based on the listener for this.getViewModel().diffPath$
 - gr-dropdown-list.willUpdate is called based on the re-render of #8, it still has the old path. It's items' have changed but not its `path.
 - This triggers the spin-locking back and forth.

Google-Bug-Id: b/296388347
Release-Notes: skip
Change-Id: I88196b34ddb037809ece6952555cb82e41171ad2
(cherry picked from commit 687f1203adf46755149dbdcec0069fb6b7571dfa)

1 files changed, 1 insertions, 1 deletions

diff --git a/polygerrit-ui/app/elements/shared/gr-dropdown-list/gr-dropdown-list.ts b/polygerrit-ui/app/elements/shared/gr-dropdown-list/gr-dropdown-list.ts
index 9b74e24221..465afce951 100644
--- a/polygerrit-ui/app/elements/shared/gr-dropdown-list/gr-dropdown-list.ts
+++ b/polygerrit-ui/app/elements/shared/gr-dropdown-list/gr-dropdown-list.ts
@@ -187,7 +187,7 @@ export class GrDropdownList extends LitElement {
   }
 
   protected override willUpdate(changedProperties: PropertyValues): void {
-    if (changedProperties.has('items') || changedProperties.has('value')) {
+    if (changedProperties.has('value')) {
       this.handleValueChange();
     }
   }