Address final feedback in RFC 190 (#3907)

During the review of [RFC 190](web-platform-tests/rfcs#190),
we agreed that we should:
- Remove the button when in interop and allow this to be reachable by
  query parameter only.

This change does that by removing the button added in #3753

The idea is to allow users to accomplish their
workflows with view=test without confusing others. Another RFC would be
needed to add a button.

Additionally, since this RFC has been accepted, we can remove the
feature flag gating it.

webapp/components/wpt-flags.js

@@ -47,7 +47,6 @@ Object.defineProperty(wpt, 'ClientSideFeatures', {
  'queryBuilder',
  'queryBuilderSHA',
  'showBSF',
- 'showViewEqTest',
  'structuredQueries',
  'triageMetadataUI',
  'webPlatformTestsLive',
@@ -259,11 +258,6 @@ class WPTFlagsEditor extends FlagsEditorClass(/*environmentFlags*/ false) {
  Enable Browser Specific Failures graph
  </paper-checkbox>
  </paper-item>
- <paper-item>
- <paper-checkbox checked="{{showViewEqTest}}">
- Enable view=test query parameter
- </paper-checkbox>
- </paper-item>
 `;
  }
 

webapp/views/wpt-results.js

@@ -262,9 +262,6 @@ class WPTResults extends AmendMetadataMixin(Pluralizer(WPTColors(WPTFlags(PathIn
  <template is="dom-if" if="[[shouldDisplayToggle(canViewInteropScores, pathIsATestFile)]]">
  <div class="channel-area">
  <paper-button id="toggleInterop" class\$="[[ interopButtonClass(view) ]]" on-click="clickInterop">Interop View</paper-button>
- <template is="dom-if" if="[[showViewEqTest]]">
- <paper-button id="toggleTestView" class\$="[[ testViewButtonClass(view) ]]" on-click="clickTestView">Test View</paper-button>
- </template>
  <paper-button id="toggleDefault" class\$="[[ defaultButtonClass(view) ]]" on-click="clickDefault">Default View</paper-button>
  </div>
  </template>
@@ -1010,10 +1007,6 @@ class WPTResults extends AmendMetadataMixin(Pluralizer(WPTColors(WPTFlags(PathIn
  return canViewInteropScores && !pathIsATestFile;
  }
 
- testViewButtonClass(view) {
- return (view === VIEW_ENUM.Test) ? 'selected' : 'unselected';
- }
-
  interopButtonClass(view) {
  return (view === VIEW_ENUM.Interop) ? 'selected' : 'unselected';
  }
@@ -1029,18 +1022,6 @@ class WPTResults extends AmendMetadataMixin(Pluralizer(WPTColors(WPTFlags(PathIn
  this.view = VIEW_ENUM.Interop;
  }
 
- clickTestView() {
- if (!this.showViewEqTest) {
- // Do nothing if the `showViewEqTest` feature flag is not enabled.
- return;
- }
-
- if (this.isTestView()) {
- return;
- }
- this.view = VIEW_ENUM.Test;
- }
-
  clickDefault() {
  if (this.isDefaultView()) {
  return;
@@ -1085,8 +1066,7 @@ class WPTResults extends AmendMetadataMixin(Pluralizer(WPTColors(WPTFlags(PathIn
  }
 
  isTestView() {
- // If the `showViewEqTest` feature flag is not active, return false immediately.
- return this.showViewEqTest && this.view === VIEW_ENUM.Test;
+ return this.view === VIEW_ENUM.Test;
  }
 
  getTotalsClass(totalInfo) {