Enable Fragment refs in Experimental

[sebmarkbage]

That we can test it out in Next.js router conditionally when experimental is on for other reasons.

[react-sizebot]

Comparing: c2a1961...65f4409

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.js	=	6.68 kB	6.68 kB	+0.05%	1.83 kB	1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	=	517.29 kB	517.29 kB	=	92.26 kB	92.26 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.69 kB	6.69 kB	=	1.83 kB	1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js	+1.56%	608.06 kB	617.58 kB	+1.52%	107.88 kB	109.52 kB
facebook-www/ReactDOM-prod.classic.js	=	653.67 kB	653.67 kB	=	115.18 kB	115.18 kB
facebook-www/ReactDOM-prod.modern.js	=	643.95 kB	643.95 kB	=	113.59 kB	113.59 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-experimental/react-dom/cjs/react-dom-client.production.js	+1.56%	608.06 kB	617.58 kB	+1.52%	107.88 kB	109.52 kB
oss-experimental/react-dom/cjs/react-dom-unstable_testing.production.js	+1.47%	622.82 kB	631.99 kB	+1.41%	111.52 kB	113.08 kB
oss-experimental/react-dom/cjs/react-dom-profiling.profiling.js	+1.43%	663.51 kB	673.03 kB	+1.43%	116.58 kB	118.25 kB
oss-experimental/react-dom/cjs/react-dom-client.development.js	+1.00%	1,092.88 kB	1,103.78 kB	+1.02%	182.80 kB	184.66 kB
oss-experimental/react-dom/cjs/react-dom-profiling.development.js	+0.98%	1,109.28 kB	1,120.18 kB	+1.00%	185.64 kB	187.50 kB
oss-experimental/react-dom/cjs/react-dom-unstable_testing.development.js	+0.95%	1,109.83 kB	1,120.33 kB	+0.93%	186.58 kB	188.32 kB
oss-experimental/react-reconciler/cjs/react-reconciler.production.js	+0.85%	461.46 kB	465.38 kB	+0.64%	74.17 kB	74.64 kB
oss-experimental/react-reconciler/cjs/react-reconciler.profiling.js	+0.76%	514.46 kB	518.39 kB	+0.58%	82.15 kB	82.63 kB
oss-experimental/react-reconciler/cjs/react-reconciler.development.js	+0.50%	757.90 kB	761.71 kB	+0.40%	119.25 kB	119.73 kB
oss-experimental/react-art/cjs/react-art.production.js	+0.35%	339.32 kB	340.49 kB	+0.25%	57.38 kB	57.52 kB
oss-experimental/react-art/cjs/react-art.development.js	+0.20%	634.70 kB	635.99 kB	+0.13%	100.67 kB	100.80 kB

Generated by 🚫 dangerJS against 65f4409