DevTools: [CSS] promisify CSS domain

Source/devtools/front_end/platform/utilities.js

Index: Source/devtools/front_end/platform/utilities.js
diff --git a/Source/devtools/front_end/platform/utilities.js b/Source/devtools/front_end/platform/utilities.js
index ea7a2859cb598d0b6fa2459abf511deec6b4c29d..824b61b6004c2b63a1408cc63f628f38cd795154 100644
--- a/Source/devtools/front_end/platform/utilities.js
+++ b/Source/devtools/front_end/platform/utilities.js
@@ -1483,3 +1483,15 @@ Promise.prototype.spread = function(callback)
         return callback.apply(null, arg);
     }
 }
+
+/**
+ * @param {T} defaultValue
+ * @return {!Promise.<T>}
+ * @template T
+ */
+Promise.prototype.catchException = function(defaultValue) {
+    return this.catch(function (error) {
+        console.error(error);
+        return defaultValue;
+    });
+}