Add support for console.time()

[nchevobbe]

Add support for console.time() and console.timeEnd()

I'm working on it right now

[nchevobbe]

I was curious to see what the code below output in the current console :

console.time();
console.timeEnd();

-> We don't show anything.
In Chrome, they output :
default: 2544.671ms

I think it might make sense to have this too in our console. I think this might require some change server side, because in the code above, the message packet does not have the timer object at all.

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Another test I ran was :
console.timeEnd("foo");
i.e. , a timeEnd() call without a prior time() call, and if in Firefox it does not show anything, in Chrome it awkwardly show a duration (of what ? I don't know)

Maybe for this case we could output a message saying that prior time() call was not found allowing the user to know what's happening if they made a typo ?

[linclark]

This will land in m-c in Bug 1295347