Clean up creating handles from `this`.

Make these member functions static and take an additional
parameter `Handle<.> h_this`. Callers mostly already have
a Handle<> to pass, so we avoid an extra StackHandleScope.
This pattern was already used for some functions.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing --interpreter
Change-Id: I4f4478b0526bcb2f3c23305d3b3cc4a65fff9ff5
diff --git a/openjdkjvmti/ti_class.cc b/openjdkjvmti/ti_class.cc
index 7537f28..988274b 100644
--- a/openjdkjvmti/ti_class.cc
+++ b/openjdkjvmti/ti_class.cc
@@ -213,7 +213,8 @@
       art::StackHandleScope<2> hs(self);
       // Save the results of all the non-retransformable agents.
       // First allocate the ClassExt
-      art::Handle<art::mirror::ClassExt> ext(hs.NewHandle(klass->EnsureExtDataPresent(self)));
+      art::Handle<art::mirror::ClassExt> ext =
+          hs.NewHandle(art::mirror::Class::EnsureExtDataPresent(klass, self));
       // Make sure we have a ClassExt. This is fine even though we are a temporary since it will
       // get copied.
       if (ext.IsNull()) {