[interpreter] Bytecode register optimizer.

test/cctest/interpreter/bytecode_expectations/CallRuntime.golden

 #
 # Autogenerated by generate-bytecode-expectations.
 #
 
 ---
 pool type: mixed
 execute: yes
 wrap: no
 test function name: f
 
@@ skipping 14 matching lines @@
 constant pool: [
 ]
 handlers: [
 ]
 
 ---
 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: [
 ]
 handlers: [
 ]
 
 ---
 snippet: "
   function f() { return %Add(1, 2) }
@@ skipping 31 matching lines @@
                 B(Star), R(1),
                 B(CallJSRuntime), U8(122), R(0), U8(2),
   /*   44 S> */ B(Return),
 ]
 constant pool: [
   InstanceType::FIXED_ARRAY_TYPE,
 ]
 handlers: [
 ]