as.numeric for POSIXct to prevent overflow

[MichaelChirico]

Closes #3780

Alternative is to check abs(as.numeric(x)) <= .Machine$integer.max & is as.integer/as.numeric as appropriate, but I'm not sure the balance between the abs check and efficiency of as.integer vis-a-vis as.numeric

[codecov]

Codecov Report

Merging #3781 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #3781   +/-   ##
=======================================
  Coverage   99.41%   99.41%           
=======================================
  Files          71       71           
  Lines       13199    13199           
=======================================
  Hits        13122    13122           
  Misses         77       77

Impacted Files	Coverage Δ
R/IDateTime.R	100% <100%> (ø)	⬆️

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[codecov]

Codecov Report

Merging #3781 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #3781   +/-   ##
=======================================
  Coverage   99.41%   99.41%           
=======================================
  Files          71       71           
  Lines       13242    13242           
=======================================
  Hits        13165    13165           
  Misses         77       77

Impacted Files	Coverage Δ
R/IDateTime.R	100% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 463ee57...2c65416. Read the comment docs.

[jangorecki]

LGTM