Split function block scoping into a separate flag

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 59381b70c13b4b96b041a858f312e73f7e5943a4..aebf72cf5c959d6d3a6ca7cc06db5f5630c19c41 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -185,17 +185,18 @@ DEFINE_IMPLICATION(es_staging, harmony)
 DEFINE_BOOL(legacy_const, true, "legacy semantics for const in sloppy mode")
 
 // Features that are still work in progress (behind individual flags).
-#define HARMONY_INPROGRESS(V)                                   \
-  V(harmony_modules, "harmony modules")                         \
-  V(harmony_regexps, "harmony regular expression extensions")   \
-  V(harmony_proxies, "harmony proxies")                         \
-  V(harmony_sloppy, "harmony features in sloppy mode")          \
-  V(harmony_sloppy_let, "harmony let in sloppy mode")           \
-  V(harmony_unicode_regexps, "harmony unicode regexps")         \
-  V(harmony_reflect, "harmony Reflect API")                     \
-  V(harmony_destructuring, "harmony destructuring")             \
-  V(harmony_sharedarraybuffer, "harmony sharedarraybuffer")     \
-  V(harmony_atomics, "harmony atomics")                         \
+#define HARMONY_INPROGRESS(V)                                         \
+  V(harmony_modules, "harmony modules")                               \
+  V(harmony_regexps, "harmony regular expression extensions")         \
+  V(harmony_proxies, "harmony proxies")                               \
+  V(harmony_sloppy, "harmony features in sloppy mode")                \
+  V(harmony_sloppy_function, "harmony sloppy function block scoping") \
+  V(harmony_sloppy_let, "harmony let in sloppy mode")                 \
+  V(harmony_unicode_regexps, "harmony unicode regexps")               \
+  V(harmony_reflect, "harmony Reflect API")                           \
+  V(harmony_destructuring, "harmony destructuring")                   \
+  V(harmony_sharedarraybuffer, "harmony sharedarraybuffer")           \
+  V(harmony_atomics, "harmony atomics")                               \
   V(harmony_simd, "harmony simd")
 
 // Features that are complete (but still behind --harmony/es-staging flag).