Remove ThrowLocation.

Note that this is a cleanup change, and has no functionality change.
The ThrowLocation had no use anymore.

Change-Id: I3d2126af1dc673cec3a0453ff3d56a172663a5f6
diff --git a/runtime/native/java_lang_String.cc b/runtime/native/java_lang_String.cc
index 4ea2546..6afe83b 100644
--- a/runtime/native/java_lang_String.cc
+++ b/runtime/native/java_lang_String.cc
@@ -29,7 +29,7 @@
 static jint String_compareTo(JNIEnv* env, jobject javaThis, jobject javaRhs) {
   ScopedFastNativeObjectAccess soa(env);
   if (UNLIKELY(javaRhs == NULL)) {
-    ThrowNullPointerException(NULL, "rhs == null");
+    ThrowNullPointerException("rhs == null");
     return -1;
   } else {
     return soa.Decode<mirror::String*>(javaThis)->CompareTo(soa.Decode<mirror::String*>(javaRhs));