ART: Do not use std::<container>::at().

These functions are specified as throwing std::out_of_range
and we do not use exceptions.

Test: m
Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Change-Id: I67c365ed6d779c101a18b9f386c751c48ca76e16
diff --git a/runtime/entrypoints/entrypoint_utils.cc b/runtime/entrypoints/entrypoint_utils.cc
index e71d1fa..d902455 100644
--- a/runtime/entrypoints/entrypoint_utils.cc
+++ b/runtime/entrypoints/entrypoint_utils.cc
@@ -74,11 +74,11 @@
     }
     for (size_t i = 0; i < args.size(); ++i) {
       if (shorty[i + 1] == 'L') {
-        jobject val = args.at(i).l;
+        jobject val = args[i].l;
         soa.Env()->SetObjectArrayElement(args_jobj, i, val);
       } else {
         JValue jv;
-        jv.SetJ(args.at(i).j);
+        jv.SetJ(args[i].j);
         mirror::Object* val = BoxPrimitive(Primitive::GetType(shorty[i + 1]), jv).Ptr();
         if (val == nullptr) {
           CHECK(soa.Self()->IsExceptionPending());