Use LEB for br_table (#738)

Author: titzer

BinaryEncoding.md

@@ -461,9 +461,9 @@ The `br_table` operator has an immediate operand which is encoded as follows:
 | Field | Type | Description |
 | ---- | ---- | ---- |
 | arity | `varuint1` | number of arguments |
-| target_count | `varuint32` | number of targets in the target_table |
-| target_table | `uint32*` | target entries that indicate an outer block or loop to which to break |
-| default_target | `uint32` | an outer block or loop to which to break in the default case |
+| target_count | `varuint32` | number of entries in the target_table |
+| target_table | `varuint32*` | target entries that indicate an outer block or loop to which to break |
+| default_target | `varuint32` | an outer block or loop to which to break in the default case |
 
 The `br_table` operator implements an indirect branch. It accepts an optional value argument
 (like other branches) and an additional `i32` expression as input, and