Extract to local variable quick assist should not be offered when there is no change

[jjohnstn]

In the following example:

private class UtilClass {
    public static int combineHashCodes(int a, int b) {
        return a + b;
    }
}
@Override
public int hashCode() {
    int k = this.parent == null ? super.hashCode() :
    UtilClass.combineHashCodes(getElementName().hashCode(), this.parent.hashCode());
    return k;
}

Trying to extract the UtilClass.combineHashCodes() call in the conditional should not offer to put this into a local variable because the ExtractTempRefactoring code will not know whether moving the call in front of the conditional test will cause a logic change or possibly and exception to occur. Currently, the assist is offered any way and clicking on it damages the code by removing the method call from the conditional.

[jjohnstn]

Fixed by #1177