Add failing heredoc test

Author: willcosgrove

quickdraw/compilation_equivalence_cases/heredoc.rb

@@ -0,0 +1,15 @@
+class Heredoc < Phlex::HTML
+	def view_template
+		unknown {
+			p { <<~TXT }
+			  This is a heredoc.
+				It has multiple lines of text.
+				And it's all going in this <p> tag.
+			TXT
+		}
+	end
+
+	def unknown
+		yield
+	end
+end