Update gitignore file.

Bug:
Change-Id: Ife1ec84fd90b5214fccb19678d45b0e808835740
diff --git a/.gitignore b/.gitignore
index 088d2b9..0090fb9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,6 +36,8 @@
 third_party/jdwp-tests
 third_party/kotlin.tar.gz
 third_party/kotlin
+third_party/shadow
+third_party/shadow.tar.gz
 third_party/photos/*
 !third_party/photos/*.sha1
 third_party/proguard/*
@@ -56,6 +58,7 @@
 gradle-app.setting
 gradlew
 gradlew.bat
+gradle/*
 #*#
 *~
 .#*