Fixed some bugs in dom docs and recovered documentation of Canvas stuff.

tools/dom/docs/docs.json

Index: tools/dom/docs/docs.json
diff --git a/tools/dom/docs/docs.json b/tools/dom/docs/docs.json
index 9e26dfeeb6e641a33dae4961196235bdb965b21b..1cf29dd54779e24322a5a16414cfab6cfe0093ab 100644
--- a/tools/dom/docs/docs.json
+++ b/tools/dom/docs/docs.json
@@ -1 +1,42 @@
-{}
+{
+  "html": {
+    "CanvasGradient": {
+      "comment": [
+        "/**\n * An opaque canvas object representing a gradient.\n *\n * Created by calling [createLinearGradient] or [createRadialGradient] on a\n * [CanvasRenderingContext2D] object.\n *\n * Example usage:\n *\n *     var canvas = new CanvasElement(width: 600, height: 600);\n *     var ctx = canvas.context2d;\n *     ctx.clearRect(0, 0, 600, 600);\n *     ctx.save();\n *     // Create radial gradient.\n *     CanvasGradient gradient = ctx.createRadialGradient(0, 0, 0, 0, 0, 600);\n *     gradient.addColorStop(0, '#000');\n *     gradient.addColorStop(1, 'rgb(255, 255, 255)');\n *     // Assign gradients to fill.\n *     ctx.fillStyle = gradient;\n *     // Draw a rectangle with a gradient fill.\n *     ctx.fillRect(0, 0, 600, 600);\n *     ctx.save();\n *     document.body.children.add(canvas);\n *\n * See also:\n *\n * * [CanvasGradient](https://developer.mozilla.org/en-US/docs/DOM/CanvasGradient) from MDN.\n * * [CanvasGradient](http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#canvasgradient) from whatwg.\n * * [CanvasGradient](http://www.w3.org/TR/2010/WD-2dcontext-20100304/#canvasgradient) from W3C.\n */"
+      ],
+      "members": {
+        "addColorStop": [
+          "/**\n   * Adds a color stop to this gradient at the offset.\n   *\n   * The [offset] can range between 0.0 and 1.0.\n   *\n   * See also:\n   *\n   * * [Multiple Color Stops](https://developer.mozilla.org/en-US/docs/CSS/linear-gradient#Gradient_with_multiple_color_stops) from MDN.\n   */"
+        ]
+      }
+    },
+    "CanvasPattern": {
+      "comment": [
+        "/**\n * An opaque object representing a pattern of image, canvas, or video.\n *\n * Created by calling [createPattern] on a [CanvasRenderingContext2D] object.\n *\n * Example usage:\n *\n *     var canvas = new CanvasElement(width: 600, height: 600);\n *     var ctx = canvas.context2d;\n *     var img = new ImageElement();\n *     // Image src needs to be loaded before pattern is applied.\n *     img.on.load.add((event) {\n *       // When the image is loaded, create a pattern\n *       // from the ImageElement.\n *       CanvasPattern pattern = ctx.createPattern(img, 'repeat');\n *       ctx.rect(0, 0, canvas.width, canvas.height);\n *       ctx.fillStyle = pattern;\n *       ctx.fill();\n *     });\n *     img.src = \"images/foo.jpg\";\n *     document.body.children.add(canvas);\n *\n * See also:\n * * [CanvasPattern](https://developer.mozilla.org/en-US/docs/DOM/CanvasPattern) from MDN.\n * * [CanvasPattern](http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#canvaspattern) from whatwg.\n * * [CanvasPattern](http://www.w3.org/TR/2010/WD-2dcontext-20100304/#canvaspattern) from W3C.\n */"
+      ]
+    },
+    "CanvasRenderingContext": {
+      "comment": [
+        "/**\n * A rendering context for a canvas element.\n *\n * This context is extended by [CanvasRenderingContext2D] and\n * [WebGLRenderingContext].\n */"
+      ],
+      "members": {
+        "canvas": [
+          "/// Reference to the canvas element to which this context belongs."
+        ]
+      }
+    },
+    "HTMLCanvasElement": {
+      "members": {
+        "height": [
+          "/// The height of this canvas element in CSS pixels."
+        ],
+        "toDataURL": [
+          "/**\n   * Returns a data URI containing a representation of the image in the\n   * format specified by type (defaults to 'image/png').\n   *\n   * Data Uri format is as follow `data:[<MIME-type>][;charset=<encoding>][;base64],<data>`\n   *\n   * Optional parameter [quality] in the range of 0.0 and 1.0 can be used when requesting [type]\n   * 'image/jpeg' or 'image/webp'. If [quality] is not passed the default\n   * value is used. Note: the default value varies by browser.\n   *\n   * If the height or width of this canvas element is 0, then 'data:' is returned,\n   * representing no data.\n   *\n   * If the type requested is not 'image/png', and the returned value is\n   * 'data:image/png', then the requested type is not supported.\n   *\n   * Example usage:\n   *\n   *     CanvasElement canvas = new CanvasElement();\n   *     var ctx = canvas.context2d\n   *     ..fillStyle = \"rgb(200,0,0)\"\n   *     ..fillRect(10, 10, 55, 50);\n   *     var dataUrl = canvas.toDataURL(\"image/jpeg\", 0.95);\n   *     // The Data Uri would look similar to\n   *     // 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA\n   *     // AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO\n   *     // 9TXL0Y4OHwAAAABJRU5ErkJggg=='\n   *     //Create a new image element from the data URI.\n   *     var img = new ImageElement();\n   *     img.src = dataUrl;\n   *     document.body.children.add(img);\n   *\n   * See also:\n   *\n   * * [Data URI Scheme](http://en.wikipedia.org/wiki/Data_URI_scheme) from Wikipedia.\n   *\n   * * [HTMLCanvasElement](https://developer.mozilla.org/en-US/docs/DOM/HTMLCanvasElement) from MDN.\n   *\n   * * [toDataUrl](http://dev.w3.org/html5/spec/the-canvas-element.html#dom-canvas-todataurl) from W3C.\n   */"
+        ],
+        "width": [
+          "/// The width of this canvas element in CSS pixels."
+        ]
+      }
+    }
+  }
+}