Fix DOMProperty bitmask checking

[Was previously "Fix HAS_POSITIVE_NUMERIC_VALUE properties" — code and title updated to fix underlying problem]

The bitmask checks in `DOMProperty` do not properly handle masks with more than one bit set; specifically, properties marked `HAS_NUMERIC_VALUE` are also passing tests for `HAS_POSITIVE_NUMERIC_VALUE`, introduced in 5c9d616735c4c5c31fb68b789c8c6f3afeae9592.

This bug manifests when attempting to use the `start` attribute on an ordered list to make the list start at 0. The following test case (also available [on JSFiddle](http://jsfiddle.net/BinaryMuse/cjqzuuqb/) demonstrates):

```html
<div id="list-1"></div>
<div id="list-2"></div>
<div id="list-3"></div>
<p>HTML starting at 0:
    <ol start="0">
        <li>First</li>
        <li>Second</li>
        <li>Third</li>
    </ol>
</p>
```

```javascript
/** @jsx React.DOM */

var List = React.createClass({
    render: function() {
        return (
            <p>React starting at {this.props.start}:
                <ol start={this.props.start}>
                    <li>First</li>
                    <li>Second</li>
                    <li>Third</li>
                </ol>
            </p>
        );
    }
});
 
React.renderComponent(<List start="1" />, document.getElementById("list-1"));
React.renderComponent(<List start="0" />, document.getElementById("list-2"));
React.renderComponent(<List start="5" />, document.getElementById("list-3"));
```

The output of the above is:

```
React starting at 1:

  1. First
  2. Second
  3. Third

React starting at 0:

  1. First
  2. Second
  3. Third

React starting at 5:

  5. First
  6. Second
  7. Third

HTML starting at 0:

  0. First
  1. Second
  2. Third
```