Enable the memory measurement API by default

Intent to ship: http://bit.ly/memory-i2s

Bug: 1085129,1048745
Change-Id: I4391fae4374c5bd1b126d996cebd6c63adb30407
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2624547Reviewed-by: Yoav Weiss <yoavweiss@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843440}

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -1170,8 +1170,7 @@
     },
     {
       name:"MeasureMemory",
-      origin_trial_feature_name: "MeasureMemory",
-      status:"experimental",
+      status:"stable",
     },
     {
       name: "MediaCapabilitiesDynamicRange",

third_party/blink/web_tests/virtual/stable/fast/dom/Window/window-properties-performance-expected.txt

@@ -19,6 +19,7 @@ window.performance.getEntriesByName [function]
 window.performance.getEntriesByType [function]
 window.performance.mark [function]
 window.performance.measure [function]
+window.performance.measureUserAgentSpecificMemory [function]
 window.performance.memory [object MemoryInfo]
 window.performance.memory.jsHeapSizeLimit [number]
 window.performance.memory.totalJSHeapSize [number]

third_party/blink/web_tests/virtual/stable/webexposed/global-interface-listing-expected.txt

@@ -5020,6 +5020,7 @@ interface Performance : EventTarget
     method getEntriesByType
     method mark
     method measure
+    method measureUserAgentSpecificMemory
     method now
     method setResourceTimingBufferSize
     method toJSON