DevTools: introduce basic logpoint experiment

Behind an experiment, a new context menu option in the Sources gutter
allows adding a logpoint. Future CLs will tackle editing a breakpoint
type and UI changes.

Logpoints `console.log` a message instead of pausing.

Bug: 700519
Change-Id: Ib33c1a84de4fbc06b6fde6e2e3dd7628e3896d64
Reviewed-on: https://chromium-review.googlesource.com/c/1330079
Commit-Queue: Erik Luo <[email protected]>
Reviewed-by: Joel Einbinder <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#613223}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 098da25c94fcb874ef01f853e7cb11f3759aabc8
diff --git a/front_end/main/Main.js b/front_end/main/Main.js
index d22ecf4..ac19941 100644
--- a/front_end/main/Main.js
+++ b/front_end/main/Main.js
@@ -119,6 +119,7 @@
     Runtime.experiments.register('protocolMonitor', 'Protocol Monitor');
     Runtime.experiments.register('samplingHeapProfilerTimeline', 'Sampling heap profiler timeline', true);
     Runtime.experiments.register('sourceDiff', 'Source diff');
+    Runtime.experiments.register('sourcesLogpoints', 'Sources: logpoints');
     Runtime.experiments.register('sourcesPrettyPrint', 'Automatically pretty print in the Sources Panel');
     Runtime.experiments.register(
         'stepIntoAsync', 'Introduce separate step action, stepInto becomes powerful enough to go inside async call');