[bigint] Adapt Object::SameValueZero.

Also add tests for Object::SameValue.

R=jkummerow@chromium.org

Bug: v8:6791
Change-Id: I0611044dcfee4c6ba836629cf82d1589135e4ab0
Reviewed-on: https://chromium-review.googlesource.com/712034Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48486}

src/objects.cc

@@ -2409,8 +2409,6 @@ Smi* Object::GetOrCreateHash(Isolate* isolate) {
 bool Object::SameValue(Object* other) {
   if (other == this) return true;
 
-  // The object is either a number, a name, an odd-ball,
-  // a real JS object, or a Harmony proxy.
   if (IsNumber() && other->IsNumber()) {
     double this_value = Number();
     double other_value = other->Number();
@@ -2434,8 +2432,6 @@ bool Object::SameValue(Object* other) {
 bool Object::SameValueZero(Object* other) {
   if (other == this) return true;
 
-  // The object is either a number, a name, an odd-ball,
-  // a real JS object, or a Harmony proxy.
   if (IsNumber() && other->IsNumber()) {
     double this_value = Number();
     double other_value = other->Number();
@@ -2446,6 +2442,9 @@ bool Object::SameValueZero(Object* other) {
   if (IsString() && other->IsString()) {
     return String::cast(this)->Equals(String::cast(other));
   }
+  if (IsBigInt() && other->IsBigInt()) {
+    return BigInt::Equal(BigInt::cast(this), BigInt::cast(other));
+  }
   return false;
 }
 

test/mjsunit/harmony/bigint.js

@@ -286,6 +286,18 @@ const six = BigInt(6);
   assertTrue(Reflect.defineProperty(obj, 'foo', {value: zero}));
   assertTrue(Reflect.defineProperty(obj, 'foo', {value: another_zero}));
   assertFalse(Reflect.defineProperty(obj, 'foo', {value: one}));
+}{
+  assertTrue(%SameValue(zero, zero));
+  assertTrue(%SameValue(zero, another_zero));
+
+  assertFalse(%SameValue(zero, +0));
+  assertFalse(%SameValue(zero, -0));
+
+  assertFalse(%SameValue(+0, zero));
+  assertFalse(%SameValue(-0, zero));
+
+  assertTrue(%SameValue(one, one));
+  assertTrue(%SameValue(one, another_one));
 }
 
 // SameValueZero
@@ -328,6 +340,18 @@ const six = BigInt(6);
 
   assertTrue(new Map([[one, 42]]).has(one));
   assertTrue(new Map([[one, 42]]).has(another_one));
+}{
+  assertTrue(%SameValueZero(zero, zero));
+  assertTrue(%SameValueZero(zero, another_zero));
+
+  assertFalse(%SameValueZero(zero, +0));
+  assertFalse(%SameValueZero(zero, -0));
+
+  assertFalse(%SameValueZero(+0, zero));
+  assertFalse(%SameValueZero(-0, zero));
+
+  assertTrue(%SameValueZero(one, one));
+  assertTrue(%SameValueZero(one, another_one));
 }
 
 // ToNumber