Instead of searching for the operator in the string representation of
the whole expression, consider the operator's start to be the
first non-whitespace non-dot character _after_ the LHS of the infix
expression.
This fixes cases like this:
```
assert("Name in " in listOf("Hello", "World"))
| |
| [Hello, World]
false
```
^KT-66208 Fixed
Sergej Jaskiewicz
54c58671fb