RTE fails to parse valid HTML, throws stack trace error

When copying and pasting rich content - for example links or simple text styling - from one web source to another, the RTE does a decent job of parsing the HTML and converting it to the appropriate wiki markup. However, certain valid HTML is not correctly parsed, and upon attempting to save the page, a stack trace is thrown. The problematic code appears to be inline CSS where an RGB color value is presented, followed by an !important. This particular combo of code, while totally valid HTML/CSS, reliably produces an error, the full paghe stack trace of which can be viewed on the attached full_page_stack_trace.pdf.

Steps to Repro:

1. Download the attached code_copy_example.html, and load the page in your browser.
2. Highlight the large red text and copy to your clipboard.
3. Paste this into the Rich Text tab of an Edit page in Confluence.
4. Notice that the large red text is pasted normally and is displayed as large red text in the RTE.
5. Click the Save button.

Expected:
The page is saved and displayed in a way that closely matches what was shown in the RTE, aka there is larger than default red text.

Actual:
A stack trace is thrown.