Parse class static block (#12079)

Co-authored-by: Brian Ng <bng412@gmail.com>

packages/babel-parser/test/fixtures/experimental/class-static-block/nested-control-flow/input.js

@@ -0,0 +1,17 @@
+class C {
+  static foo() {}
+  static {
+    while (this.foo) {
+      if (this.foo) {
+        break;
+      } else {
+        continue;
+      }
+    }
+    class C2 {
+      bar() {
+        return;
+      }
+    }
+  }
+}