fix(datepicker): calendar panel supports multi theme scenario

[rudzikdawid]

Closes #11265
example of issue: https://codepen.io/anon/pen/GdrKPp?editors=1010

PR Checklist

Please check that your PR fulfills the following requirements:

• The commit message follows our guidelines
• Tests for the changes have been added or this is not a bug fix / enhancement
• Docs have been added, updated, or were not required

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Enhancement
[ ] Documentation content changes
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

https://codepen.io/anon/pen/GdrKPp?editors=1010
In dynamic multi theme scenario we have light background of datepicker in dark theme.
This issue only appear in multi theme scenario. With single default dark theme doesn't appear.

Issue Number:
#11265

What is the new behavior?

In multi theme scenario we should have dark background of datepicker in dark theme.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

before: dark theme in multi theme scenario

after: dark theme in multi theme scenario

[rudzikdawid]

there is something wrong with .md-datepicker-calendar-pane element in dynamic dark theme scenario
we have inside datePicker-theme.scss:

  .md-datepicker-calendar-pane {
    border-color: '{{background-hue-1}}';
  }

but inside DOM themeBuildStream() generate:

.md-default-theme .md-datepicker-calendar-pane, .md-datepicker-calendar-pane {
    border-color: rgb(255,255,255);
}

seems like missing current theme name in generated <style>

'{{background-hue-1}}' in others elements are generated to value: rgb(66,66,66) in dynamic dark theme. But from some reason .md-datepicker-calendar-pane has rgb(255,255,255) why?

[Splaktar]

LGTM

[Splaktar]

@rudzikdawid are the issues you mention in #11267 (comment) resolved? or is this still an outstanding question? This doesn't seem to be an issue with your latest changes.

[Splaktar]

Example from my testing:

Looks good!

[mmalerba]

caretaker note: there are some screendiffs due to slight change in colors, but it looks like they can all be approved