Fix default style argument to Double/Single/Decimal.Parse (#17556)

Author: stephentoub

src/mscorlib/shared/System/Double.cs

@@ -297,7 +297,7 @@ public static double Parse(String s, NumberStyles style, IFormatProvider provide
         // PositiveInfinity or NegativeInfinity for a number that is too
         // large or too small.
 
-        public static double Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
+        public static double Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Float | NumberStyles.AllowThousands, IFormatProvider provider = null)
         {
             NumberFormatInfo.ValidateParseStyleFloatingPoint(style);
             return Number.ParseDouble(s, style, NumberFormatInfo.GetInstance(provider));

src/mscorlib/shared/System/Single.cs

@@ -288,7 +288,7 @@ public static float Parse(String s, NumberStyles style, IFormatProvider provider
             return Number.ParseSingle(s, style, NumberFormatInfo.GetInstance(provider));
         }
 
-        public static float Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
+        public static float Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Float | NumberStyles.AllowThousands, IFormatProvider provider = null)
         {
             NumberFormatInfo.ValidateParseStyleFloatingPoint(style);
             return Number.ParseSingle(s, style, NumberFormatInfo.GetInstance(provider));

src/mscorlib/src/System/Decimal.cs

@@ -539,7 +539,7 @@ public static Decimal Parse(String s, NumberStyles style, IFormatProvider provid
             return Number.ParseDecimal(s, style, NumberFormatInfo.GetInstance(provider));
         }
 
-        public static decimal Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
+        public static decimal Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Number, IFormatProvider provider = null)
         {
             NumberFormatInfo.ValidateParseStyleFloatingPoint(style);
             return Number.ParseDecimal(s, style, NumberFormatInfo.GetInstance(provider));