First version of PerformanceObserver

LayoutTests/inspector/sources/debugger-async/async-callstack-performance-observer-expected.txt

Index: LayoutTests/inspector/sources/debugger-async/async-callstack-performance-observer-expected.txt
diff --git a/LayoutTests/inspector/sources/debugger-async/async-callstack-performance-observer-expected.txt b/LayoutTests/inspector/sources/debugger-async/async-callstack-performance-observer-expected.txt
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index 0000000000000000000000000000000000000000..9e442218282681b6564a69e3ebe5c96f5baddae0
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+++ b/LayoutTests/inspector/sources/debugger-async/async-callstack-performance-observer-expected.txt
@@ -0,0 +1,32 @@
+Tests asynchronous call stacks for PerformanceObserver.
+
+Set timer for test function.
+Captured call stacks in no particular order:
+Call stack:
+    0) performanceCallback (async-callstack-performance-observer.html:11)
+    [PerformanceObservation]
+    0) timeout1 (async-callstack-performance-observer.html:24)
+    [setTimeout]
+    0) testFunction (async-callstack-performance-observer.html:16)
+
+Call stack:
+    0) performanceCallback (async-callstack-performance-observer.html:11)
+    [PerformanceObservation]
+    0) timeout2 (async-callstack-performance-observer.html:30)
+    [setTimeout]
+    0) timeout1 (async-callstack-performance-observer.html:23)
+    [setTimeout]
+    0) testFunction (async-callstack-performance-observer.html:16)
+
+Call stack:
+    0) performanceCallback (async-callstack-performance-observer.html:11)
+    [PerformanceObservation]
+    0) timeout3 (async-callstack-performance-observer.html:35)
+    [setTimeout]
+    0) timeout2 (async-callstack-performance-observer.html:29)
+    [setTimeout]
+    0) timeout1 (async-callstack-performance-observer.html:23)
+    [setTimeout]
+    0) testFunction (async-callstack-performance-observer.html:16)
+
+