Extract AST JSON tests.

test/libsolidity/ASTJSON/documentation.sol

@@ -0,0 +1,17 @@
+// ---- SOURCE: a
+
+/**This contract is empty*/ contract C {}
+
+// ---- SOURCE: b
+
+/**This contract is empty
+ and has a line-breaking comment.*/
+contract C {}
+
+// ---- SOURCE: c
+
+contract C {
+  /** Some comment on Evt.*/ event Evt();
+  /** Some comment on mod.*/ modifier mod() { _; }
+  /** Some comment on fn.*/ function fn() public {}
+}