C#: Fix typos is comments.

Author: michaelnebel

csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Type.cs

@@ -39,7 +39,7 @@ private bool IsBrokenType(ITypeSymbol symbol)
             }
 
             // (1) public class { ... } is a broken type and doesn't have a name.
-            // (2) public class var { ... } is a an allowed type, but it overrides the var keyword for all uses.
+            // (2) public class var { ... } is an allowed type, but it overrides the `var` keyword for all uses.
             //     It is probably a better heuristic to treat it as a broken type.
             return string.IsNullOrEmpty(symbol.Name) || symbol.Name == "var";
         }

csharp/ql/test/library-tests/standalone/brokentypes/BrokenTypes.cs

@@ -18,7 +18,7 @@ public static void Main()
         string y1 = x1.Prop;
 
         var x2 = new C(); // Has type `var` as this overrides the implicitly typed keyword `var`.
-        var y2 = x2.Prop; // Unknown type as `x2` har type `var`.
+        var y2 = x2.Prop; // Unknown type as `x2` has type `var`.
 
         C2 x3 = new C2(); // Unknown type.
         var y3 = x3.Prop; // Unknown property of unknown type.