more browser backwards compat, polyfills

src/mol-canvas3d/canvas3d.ts

src/mol-model-props/rcsb/util.ts

src/mol-model/structure/model/types.ts

src/mol-plugin/state/actions/data-format.ts

src/mol-plugin/util/structure-selection-helper.ts

src/mol-plugin/util/viewport-screenshot.ts

src/mol-theme/color/operator-hkl.ts

src/mol-util/polyfill.ts

src/mol-util/set.ts