Add support for int-to-short in the optimizing compiler.

- Add support for the int-to-short Dex instruction in the
  optimizing compiler.
- Generate x86, x86-64 and ARM (but not ARM64) code for
  byte to short, int to short and char to short
  HTypeConversion nodes.
- Add related tests to test/422-type-conversion.

Change-Id: If1829549708d9c3473efaa641f7f0bcfa6080ae9
diff --git a/compiler/optimizing/builder.cc b/compiler/optimizing/builder.cc
index b51b6e7..b5aff4b 100644
--- a/compiler/optimizing/builder.cc
+++ b/compiler/optimizing/builder.cc
@@ -1007,6 +1007,11 @@
       break;
     }
 
+    case Instruction::INT_TO_SHORT: {
+      Conversion_12x(instruction, Primitive::kPrimInt, Primitive::kPrimShort);
+      break;
+    }
+
     case Instruction::INT_TO_CHAR: {
       Conversion_12x(instruction, Primitive::kPrimInt, Primitive::kPrimChar);
       break;