[runtime] Replace the EQUALS builtin with proper Object::Equals.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 9797f0427139b6f1cd0010bba6f01611fd159c6b..9e773c036265bffde6d27c446160bf98ebfc3413 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1048,7 +1048,7 @@ class Object {
   INLINE(bool IsFiller() const);
 
   // Extract the number.
-  inline double Number();
+  inline double Number() const;
   INLINE(bool IsNaN() const);
   INLINE(bool IsMinusZero() const);
   bool ToInt32(int32_t* value);
@@ -1083,6 +1083,9 @@ class Object {
 
   bool BooleanValue();                                      // ECMA-262 9.2.
 
+  // ES6 section 7.2.12 Abstract Equality Comparison
+  MUST_USE_RESULT static Maybe<bool> Equals(Handle<Object> x, Handle<Object> y);
+
   // ES6 section 7.2.13 Strict Equality Comparison
   bool StrictEquals(Object* that);
 
@@ -1657,6 +1660,7 @@ class Simd128Value : public HeapObject {
 
   // Equality operations.
   inline bool Equals(Simd128Value* that);
+  static inline bool Equals(Handle<Simd128Value> one, Handle<Simd128Value> two);
 
   // Checks that another instance is bit-wise equal.
   bool BitwiseEquals(const Simd128Value* other) const;
@@ -9102,6 +9106,9 @@ class Oddball: public HeapObject {
   inline byte kind() const;
   inline void set_kind(byte kind);
 
+  // ES6 section 7.1.3 ToNumber for Boolean, Null, Undefined.
+  MUST_USE_RESULT static inline Handle<Object> ToNumber(Handle<Oddball> input);
+
   DECLARE_CAST(Oddball)
 
   // Dispatched behavior.