Revert "Add Throwable.UNASSIGNED_STACK to well known fields"

This reverts commit d80668611e1982d50374da03377542a7863ba8e5.

Reason for revert: Appears to break Serialization of some Throwable subclasses.

Bug: 35910877
Bug: 109930347
Change-Id: Ic78e63229f946175c629ae76b82a277ed5f12e0f
diff --git a/runtime/well_known_classes.h b/runtime/well_known_classes.h
index bed8770..c81062f 100644
--- a/runtime/well_known_classes.h
+++ b/runtime/well_known_classes.h
@@ -86,6 +86,7 @@
   static jclass java_nio_DirectByteBuffer;
   static jclass libcore_reflect_AnnotationFactory;
   static jclass libcore_reflect_AnnotationMember;
+  static jclass libcore_util_EmptyArray;
   static jclass org_apache_harmony_dalvik_ddmc_Chunk;
   static jclass org_apache_harmony_dalvik_ddmc_DdmServer;
 
@@ -146,7 +147,6 @@
   static jfieldID java_lang_Throwable_stackTrace;
   static jfieldID java_lang_Throwable_stackState;
   static jfieldID java_lang_Throwable_suppressedExceptions;
-  static jfieldID java_lang_Throwable_UNASSIGNED_STACK;
   static jfieldID java_nio_ByteBuffer_address;
   static jfieldID java_nio_ByteBuffer_hb;
   static jfieldID java_nio_ByteBuffer_isReadOnly;
@@ -156,6 +156,7 @@
   static jfieldID java_nio_DirectByteBuffer_effectiveDirectAddress;
 
   static jfieldID java_util_Collections_EMPTY_LIST;
+  static jfieldID libcore_util_EmptyArray_STACK_TRACE_ELEMENT;
   static jfieldID org_apache_harmony_dalvik_ddmc_Chunk_data;
   static jfieldID org_apache_harmony_dalvik_ddmc_Chunk_length;
   static jfieldID org_apache_harmony_dalvik_ddmc_Chunk_offset;