Statement and expression blocks may contain C++-style comments.
A C++-style comment is started by two subsequent slashes and spans
until the next newline.

-- Expect stdout --
The result of 5 + 9 is 14.
Statement blocks may use C++ comments too: Test Another test.
-- End --

-- Testcase --
The result of 5 + 9 is {{ // The block end tag is ignored: }}
// And the expression block continues here!
5 + 9 }}.
Statement blocks may use C++ comments too: {%+
	print("Test"); // A comment.

	// Another comment.
	print(" Another test.");
%}

-- End --