No it wouldn't. All else aside, if this were the case every browser for the past decade would have been sued for including "Mozillla" and/or "MSIE" in their user-agent strings.
The important point is whether the mark is being abused as a false indication of the origin of the goods. In the case of UA strings this is plainly not the case (now). Vendor IDs are still considered to be indicative of the vendor - such an objection could be avoided by a disclaimer but this may yet not be enough if vendor-id were the common method to determine origin.
Of course their are rules against using as a TM something that is not indicative of origin (generic names of products &c.) and so if a name were needed for interoperability purposes then it could well be argued for free use.
I perhaps trolled slightly. Mea culpa.
As for Chrome browser identifying as Safari, I think not, what does Help > About say.
Well, it's somewhat unclear since "GenuineIntel" and "Intel" are not quite the same. I'm betting a good lawyer could make the case that the first explicitly seeks to confuse the user and thus dilutes the trademark. It would be interesting to see this play out in court though. I wonder if the judge could actually tell them that by using their trademark in a technical sense like this, perhaps that would cause dilution itself.
As always, with the law it's a bit more complex than it might seem.
Also note that most browser UAs explicitly states "like X."
