Enable PassiveDocumentEventListeners feature

We decide to ship the intervention of 'Uncancelable Touch Events During A Fling',
so enable 'PassiveDocumentEventListeners' feature.

Below is the link to the discussion on blink-dev
https://groups.google.com/a/chromium.org/d/topic/blink-dev/wJGmsdYxwrg/discussion

BUG=595327

Review-Url: https://codereview.chromium.org/2556723006
Cr-Commit-Position: refs/heads/master@{#437544}

content/public/common/content_features.cc

@@ -136,7 +136,7 @@ const base::Feature kPassiveDocumentEventListeners{
 // Whether we should force a touchstart and first touchmove per scroll event
 // listeners to be 'passive' during fling.
 const base::Feature kPassiveEventListenersDueToFling{
-    "PassiveEventListenersDueToFling", base::FEATURE_DISABLED_BY_DEFAULT};
+    "PassiveEventListenersDueToFling", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Pointer events support.
 const base::Feature kPointerEvents{"PointerEvent",