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/quick_exception_handler.cc b/runtime/quick_exception_handler.cc
index 8b99b9f..2dbde6f 100644
--- a/runtime/quick_exception_handler.cc
+++ b/runtime/quick_exception_handler.cc
@@ -472,7 +472,7 @@
   }
 
   static VRegKind GetVRegKind(uint16_t reg, const std::vector<int32_t>& kinds) {
-    return static_cast<VRegKind>(kinds.at(reg * 2));
+    return static_cast<VRegKind>(kinds[reg * 2]);
   }
 
   QuickExceptionHandler* const exception_handler_;