[bigint] Stage BigInts

Bug: v8:6791
Change-Id: I2799977e2a3ea275afa76edd56ee40083c1f0fe0
Reviewed-on: https://chromium-review.googlesource.com/944188Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51673}

src/flag-definitions.h

@@ -212,8 +212,7 @@ DEFINE_IMPLICATION(harmony_class_fields, harmony_private_fields)
   V(harmony_array_prototype_values, "harmony Array.prototype.values") \
   V(harmony_do_expressions, "harmony do-expressions")                 \
   V(harmony_class_fields, "harmony fields in class literals")         \
-  V(harmony_static_fields, "harmony static fields in class literals") \
-  V(harmony_bigint, "harmony arbitrary precision integers")
+  V(harmony_static_fields, "harmony static fields in class literals")
 
 // Features that are complete (but still behind --harmony/es-staging flag).
 #define HARMONY_STAGED(V)                                               \
@@ -221,7 +220,8 @@ DEFINE_IMPLICATION(harmony_class_fields, harmony_private_fields)
     "harmony disallow non undefined primitive return value from class " \
     "constructor")                                                      \
   V(harmony_public_fields, "harmony public fields in class literals")   \
-  V(harmony_private_fields, "harmony private fields in class literals")
+  V(harmony_private_fields, "harmony private fields in class literals") \
+  V(harmony_bigint, "harmony arbitrary precision integers")
 
 // Features that are shipping (turned on by default, but internal flag remains).
 #define HARMONY_SHIPPING_BASE(V)                                              \