Revert "Revert "Make OpenJDK 8 the default""

Reapply the switch to JDK 8 on aosp/master.

This reverts commit 85bddfdedffb425d85657314591a57191113806b.

Change-Id: If2e8733ba78b007d37914c0512cd6be1bd4c1e69
diff --git a/core/droiddoc.mk b/core/droiddoc.mk
index f791884..1b65611 100644
--- a/core/droiddoc.mk
+++ b/core/droiddoc.mk
@@ -209,7 +209,7 @@
                 \@$(PRIVATE_SRC_LIST_FILE) \
                 -J-Xmx1024m \
                 -XDignore.symbol.file \
-                $(if $(EXPERIMENTAL_USE_JAVA8),-Xdoclint:none) \
+                $(if $(LEGACY_USE_JAVA7),,-Xdoclint:none) \
                 $(PRIVATE_PROFILING_OPTIONS) \
                 $(addprefix -classpath ,$(PRIVATE_CLASSPATH)) \
                 $(addprefix -bootclasspath ,$(PRIVATE_BOOTCLASSPATH)) \