[turbofan] Introduce a dedicated Array type.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index 94c54ac60089a60418f1e22ae263bc2ba9e236dc..3150222b79f8ce0322ffbcf26fff40e185c04631 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -1119,11 +1119,7 @@ Type* Typer::Visitor::TypeJSCreateArguments(Node* node) {
   return Type::OtherObject();
 }
 
-
-Type* Typer::Visitor::TypeJSCreateArray(Node* node) {
-  return Type::OtherObject();
-}
-
+Type* Typer::Visitor::TypeJSCreateArray(Node* node) { return Type::Array(); }
 
 Type* Typer::Visitor::TypeJSCreateClosure(Node* node) {
   return Type::Function();
@@ -1139,7 +1135,7 @@ Type* Typer::Visitor::TypeJSCreateKeyValueArray(Node* node) {
 }
 
 Type* Typer::Visitor::TypeJSCreateLiteralArray(Node* node) {
-  return Type::OtherObject();
+  return Type::Array();
 }
 
 
@@ -1516,6 +1512,7 @@ Type* Typer::Visitor::JSCallTyper(Type* fun, Typer* t) {
 
         // Object functions.
         case kObjectAssign:
+          return Type::Receiver();
         case kObjectCreate:
           return Type::OtherObject();
         case kObjectHasOwnProperty:
@@ -1527,7 +1524,7 @@ Type* Typer::Visitor::JSCallTyper(Type* fun, Typer* t) {
         case kRegExpCompile:
           return Type::OtherObject();
         case kRegExpExec:
-          return Type::Union(Type::OtherObject(), Type::Null(), t->zone());
+          return Type::Union(Type::Array(), Type::Null(), t->zone());
         case kRegExpTest:
           return Type::Boolean();
         case kRegExpToString: