fix(web-vitals): Generate TTFB (Time to first byte) from span data #3515
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rhcarvalho
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May 10, 2021
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This is low-risk enough that we can try out 👍
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Closes #3507
Since the JS SDK generates its own
timeOrigin, the TTFB metric as measured by the web-vitals library may not match what's visualized from the captured span data. Thus, it's preferred that we generate TTFB from the span data.This also implicitly addresses negative TTFB values that could be generated from Firefox browsers.
For TTFB, we measure from the beginning of the transaction to the start of the response.
For TTFB Request Time, we measure from beginning of the request to the beginning of the response.