Add a new test for SVG image textures.

This patch adds a new test for SVG image textures.

The conformance test results for Chrome are listed below. I verified this test also passes in Safari (above r157647) and Firefox (27.0a1 (2013-10-17)).

WebGL Conformance Test Results
Version 1.0.3 (beta)

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User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1678.0 Safari/537.36
WebGL VENDOR: WebKit
WebGL VERSION: WebGL 1.0 (OpenGL ES 2.0 Chromium)
WebGL RENDERER: WebKit WebGL
Unmasked VENDOR: undefined
Unmasked RENDERER: undefined
WebGL R/G/B/A/Depth/Stencil bits (default config): 8/8/8/8/24/0

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Test Summary (9 total tests):
Tests PASSED: 9
Tests FAILED: 0
Tests TIMED OUT: 0
Tests SKIPPED: 0

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All tests PASSED


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Complete Test Results (total / pass / fail / timeout / skipped):

conformance/textures/tex-image-and-sub-image-2d-with-svg-image.html: 9 / 9 / 0 / 0 / 0

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Generated on: Mon Oct 21 2013 15:57:02 GMT-0700 (PDT)