One of the things preventing getting green crashtest runs on debug builds is that the output is so long because of all the assertions (with stacks). We're hitting our (self-imposed) log size limit (intended to catch cases of hangs that generate output). The vast majority of the assertions in a crashtest run result from assertions asserting that we don't use unconstrained sizes for intrinsic widths anymore. These have become common since we're now using NSCoordSaturating* functions a good bit, and a number of crashtests contain very large sizes that trigger the clamping that these functions do. Therefore, I propose changing these assertions into NS_WARN_IF_FALSE. This means there will still be some output in case of code using them incorrectly, but the output won't be in the form of assertions. This patch fixes the assertions that showed up in the tinderbox log; I haven't searched for other occurrences.

I noticed this because my work in bug 563584 changed the number of times we hit the assertion on this testcase, and I concluded the easiest solution was to make it not assert at all. (This just passed try.)