Some cleanups.

runtime/vm/locations.h

Index: runtime/vm/locations.h
===================================================================
--- runtime/vm/locations.h	(revision 9862)
+++ runtime/vm/locations.h	(working copy)
@@ -218,6 +218,7 @@
   }
 
   void set_in(intptr_t index, Location loc) {
+    ASSERT(!is_call() || loc.IsRegister());
     input_locations_[index] = loc;
   }
 
@@ -234,6 +235,7 @@
   }
 
   void set_temp(intptr_t index, Location loc) {
+    ASSERT(!is_call() || loc.IsRegister());
     temp_locations_[index] = loc;
   }
 
@@ -247,6 +249,7 @@
 
 
   void set_out(Location loc) {
+    ASSERT(!is_call() || loc.IsRegister());
     output_location_ = loc;
   }