Make tests runnable with Buck/OSS again

Summary:
Fixes test execution for open source:

- adds hamcrest jar and dependency, as required by buck (to not throw `"Unable to locate hamcrest on the classpath. Please add as a test dependency."`)
- enables events for OSS, to make tests pass

Reviewed By: SidharthGuglani

Differential Revision: D16202542

fbshipit-source-id: a56069de162f739b3b989961b5dc00f3d37f5849

tools/build_defs/oss/yoga_defs.bzl

@@ -191,6 +191,7 @@ def yoga_java_library(*args, **kwargs):
     native.java_library(*args, **kwargs)
 
 def yoga_java_test(*args, **kwargs):
+    kwargs["deps"] = kwargs.get("deps", []) + ["//lib/hamcrest:hamcrest"]
     native.java_test(*args, **kwargs)
 
 def yoga_prebuilt_cxx_library(*args, **kwargs):