C#: Add unsigned right shift operator class.

csharp/ql/lib/semmle/code/csharp/Callable.qll

@@ -637,7 +637,8 @@ class TrueOperator extends UnaryOperator {
  * operator (`DivOperator`), a remainder operator (`RemOperator`), an and
  * operator (`AndOperator`), an or operator (`OrOperator`), an xor
  * operator (`XorOperator`), a left shift operator (`LeftShiftOperator`),
- * a right shift operator (`RightShiftOperator`), an equals operator (`EQOperator`),
+ * a right shift operator (`RightShiftOperator`), an unsigned right shift
+ * operator(`UnsignedRightShiftOperator`), an equals operator (`EQOperator`),
  * a not equals operator (`NEOperator`), a lesser than operator (`LTOperator`),
  * a greater than operator (`GTOperator`), a less than or equals operator
  * (`LEOperator`), or a greater than or equals operator (`GEOperator`).
@@ -822,6 +823,23 @@ class RightShiftOperator extends BinaryOperator {
 /** DEPRECATED: Alias for RightShiftOperator. */
 deprecated class RShiftOperator = RightShiftOperator;
 
+/**
+ * A user-defined unsigned right shift operator (`>>>`), for example
+ *
+ * ```csharp
+ * public static Widget operator >>>(Widget lhs, Widget rhs) {
+ *   ...
+ * }
+ * ```
+ */
+class UnsignedRightShiftOperator extends BinaryOperator {
+  UnsignedRightShiftOperator() { this.getName() = ">>>" }
+
+  override string getFunctionName() { result = "op_UnsignedRightShift" }
+
+  override string getAPrimaryQlClass() { result = "UnsignedRightShiftOperator" }
+}
+
 /**
  * A user-defined equals operator (`==`), for example
  *