fix(VImg): SVG size wrong after uncached load

[YipingRuan]

Description

fix #12784 cause new bug:

Motivation and Context

How Has This Been Tested?

visually

Markup:

<template>
  <div id="app">
    <v-app>
      <v-container>
        <v-row>
          svg with height/width
          <v-img src="https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/AJ_Digital_Camera.svg"></v-img>
        </v-row>
        <v-row>
          svg no given height/width
          <v-img src="https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/410.svg"></v-img>
        </v-row>
        <v-row>
          data-url:
          <v-img src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg'%3E%3Ccircle r='50' cx='50' cy='50' fill='tomato'/%3E%3Ccircle r='41' cx='47' cy='50' fill='orange'/%3E%3Ccircle r='33' cx='48' cy='53' fill='gold'/%3E%3Ccircle r='25' cx='49' cy='51' fill='yellowgreen'/%3E%3Ccircle r='17' cx='52' cy='50' fill='lightseagreen'/%3E%3Ccircle r='9' cx='55' cy='48' fill='teal'/%3E%3C/svg%3E" />
        </v-row>
      </v-container>
    </v-app>
  </div>
</template>

<script>
  export default {

  }
</script>

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement/refactoring (non-breaking change that doesn't add any features but makes things better)

Checklist:

• The PR title is no longer than 64 characters.
• The PR is submitted to the correct branch (master for bug fixes and documentation updates, dev for new features and backwards compatible changes and next for non-backwards compatible changes).
• My code follows the code style of this project.
• I've added relevant changes to the documentation (applies to new features and breaking changes in core library)

[YipingRuan]

Include fix to stop svg polling forever (no size)