[turbofan] Introduce a dedicated Array type.

src/compiler/types.cc

Index: src/compiler/types.cc
diff --git a/src/compiler/types.cc b/src/compiler/types.cc
index e0de4ef97aad5c5874711fb0f63969cab041f5c9..b7221dad0f1b1cd2986058e63cff12b4e5084a92 100644
--- a/src/compiler/types.cc
+++ b/src/compiler/types.cc
@@ -208,6 +208,8 @@ Type::bitset BitsetType::Lub(i::Map* map) {
         return kOtherCallable;
       }
       return kOtherObject;
+    case JS_ARRAY_TYPE:
+      return kArray;
     case JS_VALUE_TYPE:
     case JS_MESSAGE_OBJECT_TYPE:
     case JS_DATE_TYPE:
@@ -216,7 +218,6 @@ Type::bitset BitsetType::Lub(i::Map* map) {
     case JS_ASYNC_GENERATOR_OBJECT_TYPE:
     case JS_MODULE_NAMESPACE_TYPE:
     case JS_ARRAY_BUFFER_TYPE:
-    case JS_ARRAY_TYPE:
     case JS_REGEXP_TYPE:  // TODO(rossberg): there should be a RegExp type.
     case JS_TYPED_ARRAY_TYPE:
     case JS_DATA_VIEW_TYPE: