figure out the list based on the hints only

examples/list.js

@@ -13,3 +13,6 @@ const hints = {
 };
 
 report.list('The same list with hints', someList, hints);
+
+report.info('The same list with just the hints');
+report.list('just the hints', hints);

src/reporters/base-reporter.js

@@ -188,7 +188,7 @@ export default class BaseReporter {
   }
 
   // TODO
-  list(key: string, items: Array<string>, hints?: Object) {}
+  list(key: string, items: Array<string>|Object, hints?: Object) {}
 
   // Outputs basic tree structure to console
   tree(key: string, obj: Trees, {force = false}: {force?: boolean} = {}) {}

src/reporters/console/console-reporter.js

@@ -134,14 +134,19 @@ export default class ConsoleReporter extends BaseReporter {
     this.log(String(value), {force: true});
   }
 
-  list(title: string, items: Array<string>, hints?: Object) {
+  list(title: string, items: Array<string>|Object, hints?: Object) {
     /**
      * Because in the original Yarn code list() is called starting with a "key:
      * string" argument that is ignored, we don't assume that a title has been
      * passed in or is a valid string, to avoid creating a breaking change.
      */
     this._logCategory('list', 'magenta', typeof title === 'string' ? this.format.bold(title) : '');
 
+    if( !Array.isArray(items) ) {
+        hints = items;
+        items = Object.keys(hints);
+    }
+
     const gutterWidth = (this._lastCategorySize || 2) - 1;
 
     if (hints) {