RELNOTES: Add a new flag that lets users change the stubbing behavior at runtime and another to always stub. The first flag is used in cr/511232461.

PiperOrigin-RevId: 511339596
Change-Id: I876d3a82f5db56522cd86f3fcb1d81acab947bf1

Author: iteriani

closure/goog/soy/soy.js

@@ -21,7 +21,7 @@ const safe = goog.require('goog.dom.safe');
 /**
  * A define to control the behavior of SoyJS. If set to true, all Soy templates
  * will check for the the presence of a stub template generated by Incremental
- * Dom, and delegate to it if present.. If it is set, then it delegates to the
+ * Dom, and delegate to it if present. If it is set, then it delegates to the
  * function instead.
  *
  * This is a define because this adds a set amount of code per template to check
@@ -30,6 +30,30 @@ const safe = goog.require('goog.dom.safe');
  */
 exports.shouldStub = goog.define('goog.soy.SHOULD_STUB', false);
 
+/**
+ * A define to always stub SoyJS with Incremental DOM templates.
+ * @define {boolean}
+ */
+exports.alwaysStub = goog.define('goog.soy.ALWAYS_STUB', false);
+
+let shouldStubAtRuntime = true;
+
+/**
+ * A runtime control for whether a Soy template will be replaced with an
+ * Incremental DOM template. This is to allow teams to run a 3-arm experiment
+ * with the default being NOOP (IDOM not not loaded), A1 (IDOM and SoyJS code
+ * loaded), and A2 (A1 but code stubbed at runtime).
+ * @return {boolean}
+ */
+exports.shouldStubAtRuntime = function() {
+  return shouldStubAtRuntime;
+};
+
+/** See above. */
+exports.disableStubbingAtRuntime = function() {
+  shouldStubAtRuntime = false;
+};
+
 /**
  * A structural interface for injected data.
  *