Some minor simplifications in code and tests.

Background:
This is actually a resubmit of an earlier cl that was
reverted because was test was less robust against
inlining changes (it assumed a virtual call would
never be inlined).

original cl: If8ada79dfd70bea991c11d2b18661b951b6c4cd4
revert cl:   I739aaaccd0509d02a62ef01e797a6d45bfe941df

Change-Id: I952680d60ff488874907f066bfdf156a45b409ba
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index adf8734..92f758d 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -2221,10 +2221,7 @@
     SetSideEffects(GetSideEffects().Union(SideEffects::CanTriggerGC()));
   }
   // Adjust method's exception status from intrinsic table.
-  switch (exceptions) {
-    case kNoThrow: SetCanThrow(false); break;
-    case kCanThrow: SetCanThrow(true); break;
-  }
+  SetCanThrow(exceptions == kCanThrow);
 }
 
 bool HNewInstance::IsStringAlloc() const {