fix(extension): Row Detail gets blanked out for no reason, fixes #546

[ghiscoding]

• it seems that when trying to find the DOM element of the row detail, we should always use the last one instead of the first one found
• final fix for issue #546

[codecov]

Codecov Report

Merging #552 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #552   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          148       148           
  Lines         9719      9719           
  Branches      3414      3414           
=========================================
  Hits          9719      9719           

Impacted Files	Coverage Δ
...lar-slickgrid/extensions/rowDetailViewExtension.ts	100.00% <100.00%> (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 324f490...58d42f7. Read the comment docs.