title: pdfMake page break effect when used canvas with type="line"
body: <p>I would appreciate if someone explain me, which one can be that case, when the canvas declaration with type "line" emit a page break, in the pdf. 
  I unable to figured out what is the cause of it. 
  If I removed all cancas, no page break in the downloaded pdf.</p>
  
  <p>Thank you in advance.</p>
  
  <p>Here is the code which I used:</p>
  
  <pre><code>var dd = {
    content: [{
        "canvas": [{
          "lineColor": "gray",
          "type": "line",
          "x1": 0,
          "y1": 0,
          "x2": 515,
          "y2": 0,
          "lineWidth": 1
        }]
      },
      {
        "margin": [5, 10, 0, 5],
        "layout": "noBorders",
        "fontSize": 10,
        "table": {
          "heights": 18,
          "widths": [110, "*", "*", "*"],
          "body": [
            [{
                "text": "Text 1",
                "margin": [10, 0, 0, 0],
                "bold": true
              },
              {
                "text": "Text 1 value"
              }
  
            ],
            [{
                "text": "Text 2",
                "margin": [10, 0, 0, 0],
                "bold": true
              },
              {
                "text": "Text 2 value"
              }
            ]
          ]
        }
      },
      {
        "canvas": [{
          "lineColor": "gray",
          "type": "line",
          "x1": 0,
          "y1": 0,
          "x2": 515,
          "y2": 0,
          "lineWidth": 1
        }]
      },
      {
        "margin": [5, 10, 0, 5],
        "layout": "noBorders",
        "fontSize": 10,
        "table": {
          "heights": 18,
          "widths": [110, "*", "*", "*"],
          "body": [
            [{
                "text": "Text 1",
                "margin": [10, 0, 0, 0],
                "bold": true
              },
              {
                "text": "Text 1 value"
              }
  
            ],
            [{
                "text": "Text 2",
                "margin": [10, 0, 0, 0],
                "bold": true
              },
              {
                "text": "Text 2 value"
              }
            ]
          ]
        }
      }
    ]
  }
  </code></pre>