Allow the graph to follow the container vertical resize

[jsiembida]

Hello,

• C3 efab2ea (latest master)
• D3 v5 (5.4.0)
• Tested browsers: latest chrome, latest safari, latest FF and IE11

Observed behavior:
When changing the vertical window size the chart only updates towards
smaller height (can only shrink). When the window is getting higher, the chart
stays at the last height. The horizontal resizing works as expected.

This is CodePen (couldn't reproduce it using jsFiddle) of the original C3:

https://codepen.io/anon/pen/aGewNy

This is CodePen with the fix applied:

https://codepen.io/anon/pen/qYejZp

Please drag the horizontal bar up and down and observe how chart follows the resizing.

regards,

jarek

[codecov-io]

Codecov Report

Merging #2376 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2376      +/-   ##
==========================================
- Coverage   77.23%   77.22%   -0.01%     
==========================================
  Files          51       51              
  Lines        4138     4137       -1     
==========================================
- Hits         3196     3195       -1     
  Misses        942      942

Impacted Files	Coverage Δ
src/core.js	89.22% <ø> (-0.02%)	⬇️

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[panthony]

Hi @jsiembida, thanks for the contribution.

Tests are required for pull requests, it ensures the changes are working as expected and serve as documentation on how the library is supposed to behave for future contributors.

Did you find out why max-height was added to begin with? Was it trying to fix a specific issue?