Make the test NPAPI plugin not handle png

This is not a feature we have/need in PPAPI

BUG=493212

Review URL: https://codereview.chromium.org/1829293002

Cr-Commit-Position: refs/heads/master@{#383437}
diff --git a/third_party/WebKit/LayoutTests/TestExpectations b/third_party/WebKit/LayoutTests/TestExpectations
index b9d6580..3895e8f 100644
--- a/third_party/WebKit/LayoutTests/TestExpectations
+++ b/third_party/WebKit/LayoutTests/TestExpectations
@@ -1381,3 +1381,6 @@
 crbug.com/592409 inspector-protocol/debugger/stepping-with-blackboxed-ranges.html [ NeedsManualRebaseline ]
 
 crbug.com/594595 [ Linux ] http/tests/security/mixedContent/websocket/insecure-websocket-in-secure-page-worker-allowed.html [ Timeout Pass ]
+
+crbug.com/493212 [ Linux ] fast/block/float/4145535Crash.html [ NeedsRebaseline ]
+crbug.com/493212 [ Linux ] fast/replaced/replaced-breaking.html [ NeedsRebaseline ]