Allows turning on checked mode on a per-isolate basis

runtime/include/dart_api.h

Index: runtime/include/dart_api.h
===================================================================
--- runtime/include/dart_api.h	(revision 43472)
+++ runtime/include/dart_api.h	(working copy)
@@ -977,6 +977,19 @@
  * "pure" dart isolate. Implement and document. */
 
 /**
+ * Enables/Disables strict compilation for the current Isolate.
+ * Strict compilation includes:
+ * - type-checking
+ * - asserts
+ * - errors on bad types
+ * - errors on bad overrides
+ *
+ * This call requires there to be a current isolate, and requires that there has
+ * not yet been any compilation for the current Isolate.
+ */
+DART_EXPORT Dart_Handle Dart_IsolateSetStrictCompilation(bool value);
+
+/**
  * Creates a full snapshot of the current isolate heap.
  *
  * A full snapshot is a compact representation of the dart heap state and