Verify robustness of if statement followed by return (`if (<cond>) return`)

[zbeekman]

If statements (vs constructs, which are multi line) are probably handled correctly, but their robustness should be checked because certain cases (say if you have a line continuation in the condition) might be problematic for the instrumentor. We do not need to worry about the alternate return form where return is followed by an integer-scalar-expression. (See #32 )