Minor optimization to display block shim

[necolas]

Avoid setting styles if they are already the default for View. The cost of each style property in React Native is relatively high, so this micro optimization can still add up.

[github-actions]

workflow: benchmarks/size

Comparison of minified (terser) and compressed (brotli) size results, measured in bytes. Smaller is better.

Results	Base	Patch	Ratio
react-strict-dom/dist/dom/index.js
· compressed	2,490	2,490	1.00
· minified	8,653	8,653	1.00
react-strict-dom/dist/dom/runtime.js
· compressed	855	855	1.00
· minified	2,435	2,435	1.00
react-strict-dom/dist/native/index.js
· compressed	16,195	16,204	1.00	+
· minified	62,798	62,970	1.00	+

[github-actions]

workflow: benchmarks/perf (native)

Comparison of performance test results, measured in operations per second. Larger is better.

Results	Base	Patch	Ratio
css.create
· small	1,131,712	1,157,486	1.02	+
· small with units	491,698	490,305	1.00	-
· small with variables	665,479	675,999	1.02	+
· several small	349,660	351,042	1.00	+
· large	200,851	199,266	0.99	-
· large with polyfills	148,001	149,460	1.01	+
· complex	103,305	103,452	1.00	+
· unsupported	210,536	209,333	0.99	-
css.createTheme
· simple theme	222,645	222,256	1.00	-
· polyfill theme	209,692	211,101	1.01	+
css.props
· small	229,273	230,588	1.01	+
· small with units	186,970	186,939	1.00	-
· small with variables	112,963	112,074	0.99	-
· small with variables of units	82,147	81,420	0.99	-
· large	96,337	96,103	1.00	-
· large with polyfills	38,341	38,160	1.00	-
· complex	22,267	22,239	1.00	-
· unsupported	137,737	137,841	1.00	+
· simple merge	158,257	158,543	1.00	+
· wide merge	16,988	16,894	0.99	-
· deep merge	16,724	16,613	0.99	-
· themed merge	32,484	32,409	1.00	-

[necolas]

This might benefit from a little more logic, because I think flexShrink has an effect if the element is block but also a flex child