[browser][non-icu] HybridGlobalization normalization unblocking APIs that became supported.

docs/design/features/hybrid-globalization.md

@@ -246,6 +246,15 @@ Using `IgnoreNonSpace` for these two with `HybridGlobalization` off, also return
 new CultureInfo("de-DE").CompareInfo.IndexOf("strasse", "stra\u00DFe", 0, CompareOptions.IgnoreNonSpace); // 0 or -1
 ```
 
+**Normalization**
+
+In HybridGlobalization all normalization types are available:
+- `FormC`,
+- `FormD`,
+- `FormKC`,
+- `FormKD`.
+
+This means, that `FormKC` and `FormKD` do not throw `PlatfromNotSupportedException`, as it happens in non-hybrid mode on Browser.
 
 ### OSX
 

src/libraries/System.Private.CoreLib/src/System/Globalization/Normalization.Icu.cs

@@ -100,8 +100,12 @@ private static void ValidateArguments(string strInput, NormalizationForm normali
         {
             Debug.Assert(strInput != null);
 
-
-            if (OperatingSystem.IsBrowser() && (normalizationForm == NormalizationForm.FormKC || normalizationForm == NormalizationForm.FormKD))
+            bool notSupported = OperatingSystem.IsBrowser() && (normalizationForm == NormalizationForm.FormKC || normalizationForm == NormalizationForm.FormKD);
+#if TARGET_BROWSER
+            if (!GlobalizationMode.Hybrid && notSupported)
+#else
+            if (notSupported)
+#endif
             {
                 // Browser's ICU doesn't contain data needed for FormKC and FormKD
                 throw new PlatformNotSupportedException();

src/libraries/System.Private.CoreLib/src/System/Text/NormalizationForm.cs

@@ -9,9 +9,7 @@ public enum NormalizationForm
     {
         FormC = 1,
         FormD = 2,
-        [UnsupportedOSPlatform("browser")]
         FormKC = 5,
-        [UnsupportedOSPlatform("browser")]
         FormKD = 6
     }
 }