[interpreter] Bytecode register optimizer.

test/cctest/interpreter/bytecode_expectations/TopLevelObjectLiterals.golden

 #
 # Autogenerated by generate-bytecode-expectations.
 #
 
 ---
 pool type: mixed
 execute: no
 wrap: no
 top level: yes
 
 ---
 snippet: "
   var a = { func: function() { } };
 "
 frame size: 5
 parameter count: 1
-bytecode array length: 44
+bytecode array length: 43
 bytecodes: [
                 B(LdaConstant), U8(0),
                 B(Star), R(1),
                 B(LdaZero),
                 B(Star), R(2),
                 B(CallRuntime), U16(Runtime::kDeclareGlobals), R(1), U8(2),
   /*    0 E> */ B(StackCheck),
   /*    8 S> */ B(LdaConstant), U8(1),
                 B(Star), R(1),
                 B(LdaZero),
                 B(Star), R(2),
                 B(CreateObjectLiteral), U8(2), U8(0), U8(1),
                 B(Star), R(4),
                 B(CreateClosure), U8(3), U8(0),
                 B(StaNamedPropertySloppy), R(4), U8(4), U8(3),
-                B(Ldar), R(4),
-                B(Star), R(3),
+                B(Mov), R(4), R(3),
                 B(CallRuntime), U16(Runtime::kInitializeVarGlobal), R(1), U8(3),
                 B(LdaUndefined),
   /*   33 S> */ B(Return),
 ]
 constant pool: [
   InstanceType::FIXED_ARRAY_TYPE,
   InstanceType::ONE_BYTE_INTERNALIZED_STRING_TYPE,
   InstanceType::FIXED_ARRAY_TYPE,
   InstanceType::SHARED_FUNCTION_INFO_TYPE,
   InstanceType::ONE_BYTE_INTERNALIZED_STRING_TYPE,
 ]
 handlers: [
 ]