test: check for AbortController existence

Running tests comparitively on older versions of Node.js that
do not have AbortController can be a pain. Only add the
AbortController to knownGlobals if it actually exists.

Signed-off-by: James M Snell <jasnell@gmail.com>

test/common/index.js

@@ -253,7 +253,6 @@ function platformTimeout(ms) {
 }
 
 let knownGlobals = [
-  AbortController,
   clearImmediate,
   clearInterval,
   clearTimeout,
@@ -264,6 +263,9 @@ let knownGlobals = [
   queueMicrotask,
 ];
 
+if (global.AbortController)
+  knownGlobals.push(global.AbortController);
+
 if (global.gc) {
   knownGlobals.push(global.gc);
 }