X87: [runtime] Replace the EQUALS builtin with proper Object::Equals.

port 54bab695 (r30747).

original commit message:

    Move the implementation of the Abstract Equality Comparison to the
    runtime and thereby remove the EQUALS dispatcher builtin. Also remove
    the various runtime entry points that were only used to support the
    EQUALS builtin.

    Now the Abstract Equality Comparison is also using the correct
    ToPrimitive implementation, which properly supports @@toPrimitive.

BUG=

Review URL: https://codereview.chromium.org/1349623002

Cr-Commit-Position: refs/heads/master@{#30780}

src/x87/code-stubs-x87.cc

@@ -1574,26 +1574,22 @@ void CompareICStub::GenerateGeneric(MacroAssembler* masm) {
   __ push(eax);
 
   // Figure out which native to call and setup the arguments.
-  if (cc == equal && strict()) {
+  if (cc == equal) {
     __ push(ecx);
-    __ TailCallRuntime(Runtime::kStrictEquals, 2, 1);
+    __ TailCallRuntime(strict() ? Runtime::kStrictEquals : Runtime::kEquals, 2,
+                       1);
   } else {
-    int context_index;
-    if (cc == equal) {
-      context_index = Context::EQUALS_BUILTIN_INDEX;
-    } else {
-      context_index = is_strong(strength())
-                          ? Context::COMPARE_STRONG_BUILTIN_INDEX
-                          : Context::COMPARE_BUILTIN_INDEX;
-      __ push(Immediate(Smi::FromInt(NegativeComparisonResult(cc))));
-    }
+    int native_context_index = is_strong(strength())
+                                   ? Context::COMPARE_STRONG_BUILTIN_INDEX
+                                   : Context::COMPARE_BUILTIN_INDEX;
+    __ push(Immediate(Smi::FromInt(NegativeComparisonResult(cc))));
 
     // Restore return address on the stack.
     __ push(ecx);
 
     // Call the native; it returns -1 (less), 0 (equal), or 1 (greater)
     // tagged as a small integer.
-    __ InvokeBuiltin(context_index, JUMP_FUNCTION);
+    __ InvokeBuiltin(native_context_index, JUMP_FUNCTION);
   }
 
   __ bind(&miss);