Cache type model

[dstallenberg]

Add caching to type probability calculation in type model.

[coveralls]

Pull Request Test Coverage Report for Build 7170172455

Warning: This coverage report may be inaccurate.

We've detected an issue with your CI configuration that might affect the accuracy of this pull request's coverage report.
To ensure accuracy in future PRs, please see these guidelines.
A quick fix for this PR: rebase it; your next report should be accurate.

• 0 of 8 (0.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 46.463%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/analysis-javascript/lib/type/resolving/TypeModel.ts	0	8	0.0%

Files with Coverage Reduction	New Missed Lines	%
libraries/analysis-javascript/lib/type/resolving/TypeModel.ts	1	21.85%

Totals
Change from base Build 7169826469:	-0.1%
Covered Lines:	1540
Relevant Lines:	3063

---

💛 - Coveralls