[interpreter] Bytecode register optimizer.

test/cctest/interpreter/bytecode_expectations/CallRuntime.golden

Index: test/cctest/interpreter/bytecode_expectations/CallRuntime.golden
diff --git a/test/cctest/interpreter/bytecode_expectations/CallRuntime.golden b/test/cctest/interpreter/bytecode_expectations/CallRuntime.golden
index c5e9c4dcddc1a1bfd57c5df6a3ec9b661ccc331a..aff01ed387139cb005483f0593f1153711995f50 100644
--- a/test/cctest/interpreter/bytecode_expectations/CallRuntime.golden
+++ b/test/cctest/interpreter/bytecode_expectations/CallRuntime.golden
@@ -32,14 +32,12 @@ snippet: "
   function f(a) { return %IsArray(a) }
   f(undefined);
 "
-frame size: 1
+frame size: 0
 parameter count: 2
-bytecode array length: 11
+bytecode array length: 7
 bytecodes: [
   /*   10 E> */ B(StackCheck),
-  /*   16 S> */ B(Ldar), R(arg0),
-                B(Star), R(0),
-                B(CallRuntime), U16(Runtime::kIsArray), R(0), U8(1),
+  /*   16 S> */ B(CallRuntime), U16(Runtime::kIsArray), R(arg0), U8(1),
   /*   35 S> */ B(Return),
 ]
 constant pool: [
@@ -76,10 +74,11 @@ snippet: "
 "
 frame size: 2
 parameter count: 1
-bytecode array length: 14
+bytecode array length: 15
 bytecodes: [
   /*   10 E> */ B(StackCheck),
-  /*   15 S> */ B(LdrUndefined), R(0),
+  /*   15 S> */ B(LdaUndefined),
+                B(Star), R(0),
                 B(CreateArrayLiteral), U8(0), U8(0), U8(3),
                 B(Star), R(1),
                 B(CallJSRuntime), U8(122), R(0), U8(2),