Location information is incorrect for multi-line ERB nodes

[marcoroth]

The location information for the content and tag_closing are incorrect if the content in a ERBContentNode is multiline.

Input:

<%=
  hello
%>

Parse Tree:

@ DocumentNode (location: (1:0)-(1:12))
├── errors: []
└── children: (1 item)
    └── @ ERBContentNode (location: (1:0)-(1:12))
        ├── errors: []
        ├── tag_opening: "<%=" (location: (1:0)-(1:3))
        ├── content: "
          hello
        " (location: (1:3)-(1:10))
        ├── tag_closing: "%>" (location: (1:10)-(1:12))
        ├── parsed: true
        └── valid: true