disable EventSourceSupport for wasi

Author: pavelsavara

eng/testing/tests.browser.targets

@@ -49,7 +49,7 @@
 
     <_BundleAOTTestWasmAppForHelixDependsOn>$(_BundleAOTTestWasmAppForHelixDependsOn);PrepareForWasmBuildApp;_PrepareForAOTOnHelix</_BundleAOTTestWasmAppForHelixDependsOn>
     <UseSystemResourceKeys Condition="'$(UseSystemResourceKeys)' == ''">false</UseSystemResourceKeys>
-    <EventSourceSupport Condition="'$(EventSourceSupport)' == ''">true</EventSourceSupport>
+    <EventSourceSupport Condition="'$(EventSourceSupport)' == '' and '$(TargetOS)' != 'wasi'">true</EventSourceSupport>
     <NullabilityInfoContextSupport Condition="'$(NullabilityInfoContextSupport)' == ''">true</NullabilityInfoContextSupport>
 
     <!-- Library tests run directly from bin/ without the static web assets middleware,