refactor(runtime-html): cleanup errors, remove unused code.

[bigopon]

Some more cleanup for size, perf and error organisation.

[codecov]

Codecov Report

Merging #1771 (0663f88) into master (1c9c97c) will increase coverage by 0.25%.
The diff coverage is 76.34%.

@@            Coverage Diff             @@
##           master    #1771      +/-   ##
==========================================
+ Coverage   88.01%   88.26%   +0.25%     
==========================================
  Files         242      243       +1     
  Lines       22555    22451     -104     
  Branches     5163     5149      -14     
==========================================
- Hits        19852    19817      -35     
+ Misses       2703     2634      -69     

Impacted Files	Coverage Δ
packages/runtime-html/src/aurelia.ts	80.00% <0.00%> (ø)
packages/runtime-html/src/binding/binding-utils.ts	95.41% <0.00%> (ø)
...kages/runtime-html/src/binding/property-binding.ts	96.42% <0.00%> (ø)
...ntime-html/src/resources/binding-behaviors/attr.ts	80.00% <0.00%> (ø)
...-html/src/resources/template-controllers/repeat.ts	94.59% <0.00%> (+0.19%)	⬆️
...ages/runtime-html/src/resources/value-converter.ts	86.48% <0.00%> (ø)
...me-html/src/resources/value-converters/sanitize.ts	11.11% <0.00%> (-11.12%)	⬇️
packages/runtime-html/src/utilities.ts	96.87% <ø> (-0.10%)	⬇️
packages/runtime/src/observation/dirty-checker.ts	96.72% <ø> (ø)
packages/runtime-html/src/renderer.ts	88.52% <10.00%> (ø)
... and 45 more

... and 1 file with indirect coverage changes

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