Devtools: re-enable http/tests/devtools/network/network-initiator-chain.js

Now this CL: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/1874670
has landed, fix the test and re-enable it.

Bug: 842488
Change-Id: Ie436c7574de32e387db74697d2d205e296c4af09
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890498Reviewed-by: Lorne Mitchell <lomitch@microsoft.com>
Commit-Queue: Junyi Xiao <juxiao@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#710942}

third_party/blink/web_tests/TestExpectations

@@ -5762,9 +5762,6 @@ crbug.com/1009396 http/tests/devtools/coverage/multiple-instances-merge.js [ Pas
 crbug.com/1016772 http/tests/devtools/compiler-script-mapping.js [ Pass Failure ]
 crbug.com/1016772 http/tests/devtools/sources/debugger-ui/source-url-comment.js [ Pass Failure ]
 
-# Temporarily disabled for landing initiator chain changes in DevTools
-crbug.com/842488 http/tests/devtools/network/network-initiator-chain.js [ Pass Failure ]
-
 # Temporarily disabled to a breakpoint non-determinism issue.
 crbug.com/1019613 http/tests/devtools/sources/debugger/debug-inlined-scripts.js [ Pass Failure ]
 

third_party/blink/web_tests/http/tests/devtools/network/network-initiator-chain.js

@@ -17,7 +17,7 @@
     TestRunner.addResult('\n' + request.url());
     var graph = SDK.networkLog.initiatorGraphForRequest(request);
     TestRunner.addResult('Initiators ' + Array.from(graph.initiators).map(request => request._url));
-    TestRunner.addResult('Initiated ' + Array.from(graph.initiated).map(request => request._url));
+    TestRunner.addResult('Initiated ' + Array.from(graph.initiated.keys()).map(request => request._url));
   });
 
   TestRunner.completeTest();