[rutime] Simplify undetectable handling in Object::Equals.

According to https://www.w3.org/TR/html5/obsolete.html#dom-document-all
the undetectable bit (for document.all) only affects comparisons with
undefined and null. In particular comparisons with other values are not
affected, so we can actually simplify the handling of undetectable a
lot by only checking it when null or undefined might be involved (this
is actually in line with what the CompareIC does).

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/1764613004

Cr-Commit-Position: refs/heads/master@{#34483}

src/objects.cc

@@ -292,7 +292,7 @@ Maybe<bool> Object::Equals(Handle<Object> x, Handle<Object> y) {
         return Just(NumberEquals(*x, Handle<Oddball>::cast(y)->to_number()));
       } else if (y->IsString()) {
         return Just(NumberEquals(x, String::ToNumber(Handle<String>::cast(y))));
-      } else if (y->IsJSReceiver() && !y->IsUndetectable()) {
+      } else if (y->IsJSReceiver()) {
         if (!JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(y))
                  .ToHandle(&y)) {
           return Nothing<bool>();
@@ -310,7 +310,7 @@ Maybe<bool> Object::Equals(Handle<Object> x, Handle<Object> y) {
       } else if (y->IsBoolean()) {
         x = String::ToNumber(Handle<String>::cast(x));
         return Just(NumberEquals(*x, Handle<Oddball>::cast(y)->to_number()));
-      } else if (y->IsJSReceiver() && !y->IsUndetectable()) {
+      } else if (y->IsJSReceiver()) {
         if (!JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(y))
                  .ToHandle(&y)) {
           return Nothing<bool>();
@@ -326,7 +326,7 @@ Maybe<bool> Object::Equals(Handle<Object> x, Handle<Object> y) {
       } else if (y->IsString()) {
         y = String::ToNumber(Handle<String>::cast(y));
         return Just(NumberEquals(Handle<Oddball>::cast(x)->to_number(), *y));
-      } else if (y->IsJSReceiver() && !y->IsUndetectable()) {
+      } else if (y->IsJSReceiver()) {
         if (!JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(y))
                  .ToHandle(&y)) {
           return Nothing<bool>();
@@ -338,7 +338,7 @@ Maybe<bool> Object::Equals(Handle<Object> x, Handle<Object> y) {
     } else if (x->IsSymbol()) {
       if (y->IsSymbol()) {
         return Just(x.is_identical_to(y));
-      } else if (y->IsJSReceiver() && !y->IsUndetectable()) {
+      } else if (y->IsJSReceiver()) {
         if (!JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(y))
                  .ToHandle(&y)) {
           return Nothing<bool>();
@@ -350,7 +350,7 @@ Maybe<bool> Object::Equals(Handle<Object> x, Handle<Object> y) {
       if (y->IsSimd128Value()) {
         return Just(Simd128Value::Equals(Handle<Simd128Value>::cast(x),
                                          Handle<Simd128Value>::cast(y)));
-      } else if (y->IsJSReceiver() && !y->IsUndetectable()) {
+      } else if (y->IsJSReceiver()) {
         if (!JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(y))
                  .ToHandle(&y)) {
           return Nothing<bool>();
@@ -358,11 +358,11 @@ Maybe<bool> Object::Equals(Handle<Object> x, Handle<Object> y) {
       } else {
         return Just(false);
       }
-    } else if (x->IsJSReceiver() && !x->IsUndetectable()) {
-      if (y->IsJSReceiver()) {
+    } else if (x->IsJSReceiver()) {
+      if (y->IsUndetectable()) {
+        return Just(x->IsUndetectable());
+      } else if (y->IsJSReceiver()) {
         return Just(x.is_identical_to(y));
-      } else if (y->IsNull() || y->IsUndefined()) {
-        return Just(false);
       } else if (y->IsBoolean()) {
         y = Oddball::ToNumber(Handle<Oddball>::cast(y));
       } else if (!JSReceiver::ToPrimitive(Handle<JSReceiver>::cast(x))