[interpreter] Bytecode register optimizer.

test/cctest/interpreter/bytecode_expectations/ConstVariable.golden

Index: test/cctest/interpreter/bytecode_expectations/ConstVariable.golden
diff --git a/test/cctest/interpreter/bytecode_expectations/ConstVariable.golden b/test/cctest/interpreter/bytecode_expectations/ConstVariable.golden
index 505d3e807816c038574123939c5ea977882eea93..efd588b5d7d07ce2a4086ff8f7298ac3e5b3b37e 100644
--- a/test/cctest/interpreter/bytecode_expectations/ConstVariable.golden
+++ b/test/cctest/interpreter/bytecode_expectations/ConstVariable.golden
@@ -59,7 +59,7 @@ snippet: "
 "
 frame size: 3
 parameter count: 1
-bytecode array length: 32
+bytecode array length: 33
 bytecodes: [
                 B(LdaTheHole),
                 B(Star), R(0),
@@ -72,9 +72,9 @@ bytecodes: [
                 B(Star), R(2),
                 B(CallRuntime), U16(Runtime::kThrowReferenceError), R(2), U8(1),
                 B(CallRuntime), U16(Runtime::kThrowConstAssignError), R(0), U8(0),
-                B(Ldar), R(1),
-                B(Star), R(0),
-  /*   48 E> */ B(LdaUndefined),
+                B(Mov), R(1), R(0),
+  /*   48 E> */ B(Ldar), R(0),
+                B(LdaUndefined),
   /*   55 S> */ B(Return),
 ]
 constant pool: [
@@ -89,7 +89,7 @@ snippet: "
 "
 frame size: 3
 parameter count: 1
-bytecode array length: 36
+bytecode array length: 35
 bytecodes: [
                 B(LdaTheHole),
                 B(Star), R(0),
@@ -104,8 +104,7 @@ bytecodes: [
                 B(Star), R(2),
                 B(CallRuntime), U16(Runtime::kThrowReferenceError), R(2), U8(1),
                 B(CallRuntime), U16(Runtime::kThrowConstAssignError), R(0), U8(0),
-                B(Ldar), R(1),
-                B(Star), R(0),
+                B(Mov), R(1), R(0),
                 B(LdaUndefined),
   /*   56 S> */ B(Return),
 ]