[expr.type.conv] Clarify if ... otherwise ladder.

Fixes #1591.

Author: jensmaurer

source/expressions.tex

@@ -1770,11 +1770,11 @@
 
 \pnum
 If the initializer is a parenthesized single expression,
-the type conversion expression is equivalent (in
-definedness, and if defined in meaning) to the corresponding cast
+the type conversion expression is equivalent
+to the corresponding cast
 expression~(\ref{expr.cast}).
 \indextext{type!incomplete}%
-If the type is \cv{}~\tcode{void}
+Otherwise, if the type is \cv{}~\tcode{void}
 and the initializer is \tcode{()},
 the expression is a prvalue of the specified type
 that performs no initialization.