svg_loader: move the display property to the style

[mgrudzinska]

The display property, like any other node's style property, should be part of a node style. This ensures its correct copying and inheritance. For the 'symbol' node, which is not rendered unless it is used within a 'use' node, the display property can also be applied. Because of that it cannot be utilized during scene construction to determine whether the symbol is being defined or used within a 'use' context.

before:

after:

sample:

<svg viewBox="0 0 80 20" xmlns="http://www.w3.org/2000/svg">
  <!-- Our symbol in its own coordinate system -->
  <symbol id="myDot" width="10" height="10" viewBox="0 0 2 2" display="true">
    <circle cx="1" cy="1" r="1" />
  </symbol>

  <!-- A grid to materialize our symbol positioning -->
  <path
    d="M0,10 h80 M10,0 v20 M25,0 v20 M40,0 v20 M55,0 v20 M70,0 v20"
    fill="none"
    stroke="pink" />

  <!-- All instances of our symbol -->
  <use href="#myDot" x="5" y="5" style="opacity:1.0" />
  <use href="#myDot" x="20" y="5" style="opacity:0.8" />
  <use href="#myDot" x="35" y="5" style="opacity:0.6" />
  <use href="#myDot" x="50" y="5" style="opacity:0.4" />
  <use href="#myDot" x="65" y="5" style="opacity:0.2" />
</svg>

<svg viewBox="0 0 80 20" xmlns="http://www.w3.org/2000/svg">
  <!-- Our symbol in its own coordinate system -->
  <symbol id="myDot" width="10" height="10" viewBox="0 0 2 2">
    <circle cx="1" cy="1" r="1" />
  </symbol>

  <!-- A grid to materialize our symbol positioning -->
  <path
    d="M0,10 h80 M10,0 v20 M25,0 v20 M40,0 v20 M55,0 v20 M70,0 v20"
    fill="none"
    stroke="pink" />

  <!-- All instances of our symbol -->
  <use href="#myDot" x="5" y="5" style="opacity:1.0" />
  <use href="#myDot" x="20" y="5" style="opacity:0.8" />
  <use href="#myDot" x="35" y="5" style="opacity:0.6" />
  <use href="#myDot" x="50" y="5" style="opacity:0.4" />
  <use href="#myDot" x="65" y="5" style="opacity:0.2" />
</svg>

[mgrudzinska]

rebased

[hermet]

@JSUYA ping?