Simplify Missing Models browser splitter resize behavior

tests/test_downloads_tab_workflow_route.mjs

@@ -398,7 +398,7 @@ test('missing browser splitter keeps a compositor preview between live layout fr
 
   assert.match(missingBrowserMethodsSource, /dragThreshold:\s*4/);
   assert.match(missingBrowserMethodsSource, /layoutFrameStride:\s*3/);
-  assert.match(missingBrowserMethodsSource, /translate3d\(/);
+  assert.doesNotMatch(missingBrowserMethodsSource, /translate3d\(/);
   assert.match(
     resolverMainCssSource,
     /\.mr-missing-browser\.is-resizing::after\s*\{[^}]*pointer-events:\s*auto/s

web/css/resolver-main.css

@@ -751,12 +751,6 @@
     pointer-events: auto;
 }
 
-.mr-missing-browser.is-resizing *,
-.mr-missing-browser.is-resizing .mr-missing-list-row,
-.mr-missing-browser.is-resizing .mr-card {
-    transition: none !important;
-}
-
 #model-resolver-modal .mr-missing-list-row {
     content-visibility: auto;
     contain-intrinsic-size: 70px;
@@ -8966,11 +8960,6 @@ a.mr-image-preview-resource-name:hover {
         content-visibility: auto;
         contain-intrinsic-size: auto 220px;
     }
-
-    .mr-missing-browser.is-resizing .mr-search-results-table-wrap,
-    .mr-missing-browser.is-resizing .mr-match-row {
-        content-visibility: hidden !important;
-    }
 }
 
 #model-resolver-modal .mr-missing-detail-pane .mr-match-row.mr-best-match {

web/resolver/views/missing_browser_methods.js

@@ -1324,9 +1324,6 @@ export const missingBrowserMethods = {
         this._missingBrowserSplitListPane = listPane;
         this._missingBrowserSplitDetailPane = detailPane;
         this._missingBrowserSplitSplitter = releaseSplitter;
-        if (releaseSplitter instanceof HTMLElement) {
-            releaseSplitter.style.willChange = 'transform';
-        }
         this._missingBrowserSplitDragging = true;
         this._missingBrowserSplitStart = {
             x: event.clientX,
@@ -1345,16 +1342,9 @@ export const missingBrowserMethods = {
             bounds,
             dragThreshold: 4,
             layoutFrameStride: 3,
-            onPreview: (pendingWidth, appliedWidth) => {
+            onPreview: (pendingWidth) => {
                 this._pendingMissingBrowserSplitWidth = pendingWidth;
                 this.activateMissingBrowserSplitUi();
-                if (!(releaseSplitter instanceof HTMLElement)) return;
-
-                const visualOffset = Math.round(appliedWidth - pendingWidth);
-                releaseSplitter.style.transform = visualOffset
-                    ? `translate3d(${visualOffset}px, 0, 0)`
-                    : '';
-                releaseSplitter.style.willChange = visualOffset ? 'transform' : '';
             },
             onDrag: (width) => {
                 this._pendingMissingBrowserSplitWidth = width;