[runtime] Optimize and unify rest parameters.

src/interpreter/bytecode-array-builder.cc

Index: src/interpreter/bytecode-array-builder.cc
diff --git a/src/interpreter/bytecode-array-builder.cc b/src/interpreter/bytecode-array-builder.cc
index 7d8089b90b6e39bfd023dd8afbe883a791d0f45f..357ea0b4de2bda41ef546aced0896bb96bf94a3c 100644
--- a/src/interpreter/bytecode-array-builder.cc
+++ b/src/interpreter/bytecode-array-builder.cc
@@ -589,16 +589,6 @@ BytecodeArrayBuilder& BytecodeArrayBuilder::CreateArguments(
   return *this;
 }
 
-BytecodeArrayBuilder& BytecodeArrayBuilder::CreateRestArguments(int index) {
-  size_t index_entry =
-      GetConstantPoolEntry(Handle<Object>(Smi::FromInt(index), isolate_));
-  // This will always be the first entry in the constant pool, since the rest
-  // arguments object is created at the start of the function just after
-  // creating the arguments object.
-  CHECK(FitsInIdx8Operand(index_entry));
-  Output(Bytecode::kCreateRestArguments, static_cast<uint8_t>(index_entry));
-  return *this;
-}
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::CreateRegExpLiteral(
     Handle<String> pattern, int literal_index, int flags) {
@@ -1617,7 +1607,6 @@ Bytecode BytecodeArrayBuilder::BytecodeForStoreLookupSlot(
   return static_cast<Bytecode>(-1);
 }
 
-
 // static
 Bytecode BytecodeArrayBuilder::BytecodeForCreateArguments(
     CreateArgumentsType type) {
@@ -1626,9 +1615,10 @@ Bytecode BytecodeArrayBuilder::BytecodeForCreateArguments(
       return Bytecode::kCreateMappedArguments;
     case CreateArgumentsType::kUnmappedArguments:
       return Bytecode::kCreateUnmappedArguments;
-    default:
-      UNREACHABLE();
+    case CreateArgumentsType::kRestParameter:
+      return Bytecode::kCreateRestParameter;
   }
+  UNREACHABLE();
   return static_cast<Bytecode>(-1);
 }