[Refactoring] Remove unused ethis parameter from Expression::checkPurity
fix Issue 10981 - Contracts in pure class methods are useless
[style] fix indentation
Refactoring postblit call handling
fix Issue 11134 - Inconsistent postblit call count depends on the pointer size

Move postblit function call to front-end on CatAssignExp with appending element
Remove unused glue layer code for postblit call
fix Issue 11187 - A small transitive const bug on struct copying
Merge pull request #2639 from 9rnsr/fix11187

Issue 11187 - A small transitive const bug on struct copying
Merge pull request #2615 from 9rnsr/fix10981

Issue 10981 - Contracts in pure class methods are useless
Merge pull request #2593 from 9rnsr/fix_postblit

Issue 11134 - Inconsistent postblit call count depends on the pointer size