Bug 1596056 - Enable ESLint on reftest harness files (manual fixes). r=tnikkel

Depends on D189058

Differential Revision: https://phabricator.services.mozilla.com/D189059

.eslintignore

@@ -24,6 +24,8 @@
 # Also ignore reftest - specially crafted to produce expected output.
 **/reftest/
 **/reftests/
+# Don't ignore the reftest harness files.
+!/layout/tools/reftest/
 
 # Exclude expected objdirs.
 obj*/

layout/tools/reftest/globals.jsm

@@ -162,6 +162,7 @@ for (let [key, val] of Object.entries({
     dumpedConditionSandbox: false,
   },
 })) {
+  // eslint-disable-next-line mozilla/reject-global-this
   this[key] = val;
   EXPORTED_SYMBOLS.push(key);
 }

layout/tools/reftest/manifest.jsm

@@ -682,7 +682,7 @@ function BuildConditionSandbox(aURL) {
   sandbox.swgl = g.windowUtils.layerManagerType.startsWith(
     "WebRender (Software"
   );
-  sandbox.layersOMTC = g.windowUtils.layerManagerRemote == true;
+  sandbox.layersOMTC = !!g.windowUtils.layerManagerRemote;
 
   // Shortcuts for widget toolkits.
   sandbox.Android = xr.OS == "Android";

layout/tools/reftest/reftest-content.js

@@ -535,13 +535,13 @@ function WaitForTestEnd(
 
   var operationInProgress = false;
   function OperationInProgress() {
-    if (operationInProgress != false) {
+    if (operationInProgress) {
       LogWarning("Nesting atomic operations?");
     }
     operationInProgress = true;
   }
   function OperationCompleted() {
-    if (operationInProgress != true) {
+    if (!operationInProgress) {
       LogWarning("Mismatched OperationInProgress/OperationCompleted calls?");
     }
     operationInProgress = false;