Workaround issue where IME doesn't show up when tapping folder text

-> Various calls on EditText don't work when calling from
   onFocusChange, post instead

issue 28523980

Change-Id: Ib9972c3c5083450412340f27bdd231605957ae6f
diff --git a/src/com/android/launcher3/folder/Folder.java b/src/com/android/launcher3/folder/Folder.java
index 7dc8155..1ebe8fd 100644
--- a/src/com/android/launcher3/folder/Folder.java
+++ b/src/com/android/launcher3/folder/Folder.java
@@ -330,8 +330,13 @@
     }
 
     public void startEditingFolderName() {
-        mFolderName.setHint("");
-        mIsEditingName = true;
+        post(new Runnable() {
+            @Override
+            public void run() {
+                mFolderName.setHint("");
+                mIsEditingName = true;
+            }
+        });
     }
 
     public void dismissEditingName() {