Adding Dokka source to AOSP

This is taken from commit 4ff3d4153ca344398bffcdaaa28f1a1f6e76f6ad from
https://github.com/google/dokka, which is Google's customized fork of
Dokka (https://github.com/Kotlin/dokka).

Bug: 135767980
Test: ./gradlew :core:cleanTest :core:test
Test: ./gradlew :runners:gradle-integration-tests:clean :runners:gradle-integration-tests:test

Change-Id: I332d0b522706e353c3837f6308aac1a8340d71d3
diff --git a/core/testdata/format/throwsTag.kt b/core/testdata/format/throwsTag.kt
new file mode 100644
index 0000000..29a9c3f
--- /dev/null
+++ b/core/testdata/format/throwsTag.kt
@@ -0,0 +1,5 @@
+/**
+ * @throws IllegalArgumentException on Mondays
+ * @exception NullPointerException on Tuesdays
+ */
+fun f() {}