Suppress Linux AMD gl passthrough tests

Two webgl_conformance_gl_passthrough_tests have begun failing on Linux AMD bots.
With driver related errors. A reboot of the bot did not resolve the issue, and we have no good candidate to revert.

The consistently failing conformance/renderbuffers/renderbuffer-initialization.html will be suppressed. The flaky conformance/context/deleted-object-behavior.html will be retried.

Bug: angleproject/5213
Change-Id: I373979662c70a202d5c3cb65a8f5d9b97bd77774
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2495420Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820384}

content/test/gpu/gpu_tests/test_expectations/webgl_conformance_expectations.txt

@@ -527,6 +527,8 @@ crbug.com/965594 [ linux amd angle-opengl passthrough ] conformance/more/conform
 crbug.com/1028639 [ linux amd angle-opengl passthrough ] conformance/ogles/GL/mat/mat_009_to_016.html [ Failure ]
 crbug.com/1028639 [ linux amd angle-opengl passthrough ] conformance/ogles/GL/log2/log2_009_to_012.html [ Failure ]
 crbug.com/1060632 [ linux amd angle-opengl passthrough ] conformance/more/functions/bindBuffer.html [ RetryOnFailure ]
+crbug.com/angleproject/5213 [ linux amd-0x6613 angle-opengl passthrough ] conformance/context/deleted-object-behavior.html [ RetryOnFailure ]
+crbug.com/angleproject/5213 [ linux amd-0x6613 angle-opengl passthrough ] conformance/renderbuffers/renderbuffer-initialization.html [ Failure ]
 
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 # Android failures #