[builtins] Migrate Math.abs() to TurboFan builtins.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index ba940736dfff6e098afef099fb82b6aedbe4b75b..425b64d1ddb2bb849070ef83bee591f700fcd2da 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1669,6 +1669,9 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
     Handle<JSObject> math = factory->NewJSObject(cons, TENURED);
     DCHECK(math->IsJSObject());
     JSObject::AddProperty(global, name, math, DONT_ENUM);
+    Handle<JSFunction> math_abs =
+        SimpleInstallFunction(math, "abs", Builtins::kMathAbs, 1, true);
+    native_context()->set_math_abs(*math_abs);
     SimpleInstallFunction(math, "acos", Builtins::kMathAcos, 1, true);
     SimpleInstallFunction(math, "asin", Builtins::kMathAsin, 1, true);
     SimpleInstallFunction(math, "atan", Builtins::kMathAtan, 1, true);