Resolve map composite literal keys to constants.
Make the Composite resolve work again.
Fixed a failing test.
add constantExpressions test cases from golang spec
add test case for #989
Merge pull request #990 from bronze1man/pr-test2

add test case for #989
Merge pull request #987 from bronze1man/pr-test1

add constantExpressions test cases from golang spec
Don't create a presentation for broken elements.

Fixes #985