BUG ID: 74775 WebKit editing throws exception when monochrome color dragged onto text

STEPS TO TEST:

1. Open a color panel in any app, such as TextEdit.app.
2. Select some text in the editable region below.
3. Drag a color swatch for a monochrome color, e.g. a gray from the grayscale slider of the color panel, to the selected text.

TEST PASS: If the color changes to the desired gray, and the drag appears to be accepted, the test passes.

TEST FAIL: If the color change does not apply to the text, and the drag appears to bounce back, then the bug is probably occurring. The bug can be confirmed by looking for evidence of an uncaught exception in the system console log.

Select this text and drag a grayscale color to it.