Remove GcRoot<> static from Throwable and related classes.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 31113334
Change-Id: I8115e6413a07419ec261af3ec5068833b72b5218
diff --git a/runtime/mirror/stack_trace_element.cc b/runtime/mirror/stack_trace_element.cc
index bb3242e..ff353d8 100644
--- a/runtime/mirror/stack_trace_element.cc
+++ b/runtime/mirror/stack_trace_element.cc
@@ -18,6 +18,7 @@
 
 #include "class-inl.h"
 #include "class.h"
+#include "class_root.h"
 #include "gc/accounting/card_table-inl.h"
 #include "gc_root-inl.h"
 #include "handle_scope-inl.h"
@@ -27,26 +28,13 @@
 namespace art {
 namespace mirror {
 
-GcRoot<Class> StackTraceElement::java_lang_StackTraceElement_;
-
-void StackTraceElement::SetClass(ObjPtr<Class> java_lang_StackTraceElement) {
-  CHECK(java_lang_StackTraceElement_.IsNull());
-  CHECK(java_lang_StackTraceElement != nullptr);
-  java_lang_StackTraceElement_ = GcRoot<Class>(java_lang_StackTraceElement);
-}
-
-void StackTraceElement::ResetClass() {
-  CHECK(!java_lang_StackTraceElement_.IsNull());
-  java_lang_StackTraceElement_ = GcRoot<Class>(nullptr);
-}
-
 StackTraceElement* StackTraceElement::Alloc(Thread* self,
                                             Handle<String> declaring_class,
                                             Handle<String> method_name,
                                             Handle<String> file_name,
                                             int32_t line_number) {
   ObjPtr<StackTraceElement> trace =
-      ObjPtr<StackTraceElement>::DownCast(GetStackTraceElement()->AllocObject(self));
+      ObjPtr<StackTraceElement>::DownCast(GetClassRoot<StackTraceElement>()->AllocObject(self));
   if (LIKELY(trace != nullptr)) {
     if (Runtime::Current()->IsActiveTransaction()) {
       trace->Init<true>(declaring_class.Get(), method_name.Get(), file_name.Get(), line_number);
@@ -72,10 +60,5 @@
                                  line_number);
 }
 
-void StackTraceElement::VisitRoots(RootVisitor* visitor) {
-  java_lang_StackTraceElement_.VisitRootIfNonNull(visitor, RootInfo(kRootStickyClass));
-}
-
-
 }  // namespace mirror
 }  // namespace art