Closing over "this".

test/this/closure.wren

@@ -0,0 +1,12 @@
+class Foo {
+  getClosure {
+    return fn {
+      return this.toString
+    }
+  }
+
+  toString { return "Foo" }
+}
+
+var closure = (new Foo).getClosure
+io.write(closure.call) // expect: Foo

test/this/nested_class.wren

@@ -0,0 +1,22 @@
+class Outer {
+  method {
+    io.write(this.toString) // expect: Outer
+
+    fn {
+      io.write(this.toString) // expect: Outer
+
+      class Inner {
+        method {
+          io.write(this.toString) // expect: Inner
+        }
+        toString { return "Inner" }
+      }
+
+      (new Inner).method
+    }.call
+  }
+
+  toString { return "Outer" }
+}
+
+(new Outer).method

test/this/nested_closure.wren

@@ -0,0 +1,16 @@
+class Foo {
+  getClosure {
+    return fn {
+      return fn {
+        return fn {
+          return this.toString
+        }
+      }
+    }
+  }
+
+  toString { return "Foo" }
+}
+
+var closure = (new Foo).getClosure
+io.write(closure.call.call.call) // expect: Foo