[InstCombine] Use getInsertionPointAfterDef to get sin/cos InsertPt. (#210130)
The current logic added in
https://github.com/llvm/llvm-project/pull/194616
picks an incorrect insert point for the argument is an invoke.
Use getInsertionPointAfterDef and bail out if there is no such insert
point.
Fixes crashes in the added tests.
Fixes https://github.com/llvm/llvm-project/issues/210111