feat: resolve window.google

[jpoehnelt]

closes #224 by resolving to window.google

loader
  .load()
  .then((google) => {
    new google.maps.Map(document.getElementById("map"), mapOptions);
  })
  .catch(e => {
    // do something
  });

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[codecov]

Codecov Report

Merging #291 (21face2) into master (0845116) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #291   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines          123       123           
  Branches        25        25           
=========================================
  Hits           123       123           

Impacted Files	Coverage Δ
src/index.ts	100.00% <100.00%> (ø)

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