LibJS: Add Math.round()

Libraries/LibJS/Runtime/MathObject.cpp

@@ -38,6 +38,7 @@ MathObject::MathObject()
     put_native_function("random", random);
     put_native_function("sqrt", sqrt, 1);
     put_native_function("floor", floor, 1);
+    put_native_function("round", round, 1);
 
     put("E", Value(M_E));
     put("LN2", Value(M_LN2));
@@ -96,4 +97,16 @@ Value MathObject::floor(Interpreter& interpreter)
     return Value(::floor(number.as_double()));
 }
 
+Value MathObject::round(Interpreter& interpreter)
+{
+    if (!interpreter.argument_count())
+        return js_nan();
+
+    auto number = interpreter.argument(0).to_number();
+    if (number.is_nan())
+        return js_nan();
+    // FIXME: Use ::round() instead of ::roundf().
+    return Value(::roundf(number.as_double()));
+}
+
 }

Libraries/LibJS/Runtime/MathObject.h

@@ -42,6 +42,7 @@ private:
     static Value random(Interpreter&);
     static Value sqrt(Interpreter&);
     static Value floor(Interpreter&);
+    static Value round(Interpreter&);
 };
 
 }