[wasm][debugger] Add Browsable Attribute support.

docs/design/mono/debugger.md

@@ -18,4 +18,11 @@ Web Assembly Debugger supports usage of following attributes:
   - Stepping In/Over: results in an additional stepping need to proceed to the next line.<br><br>
 - __System.Diagnostics.DebuggerDisplay__
 - __System.Diagnostics.DebuggerTypeProxy__
-- ...
+- __System.Diagnostics.DebuggerBrowsable__ ([doc](https://docs.microsoft.com/en-us/dotnet/api/system.diagnostics.debuggerbrowsableattribute?view=net-6.0))
+   - Collapsed - displayed normally.
+   - RootHidden:
+      - Simple type - not displayed in the debugger window.
+      - Collection / Array - the values of a collection are displayed in a flat view, using  the naming convention: *rootName[idx]*.
+
+   - Never - not displayed in the debugger window.
+

src/mono/wasm/debugger/BrowserDebugProxy/DebugStore.cs

@@ -21,6 +21,8 @@
 using System.IO.Compression;
 using System.Reflection;
 using System.Collections.Immutable;
+using System.Diagnostics;
+using Microsoft.VisualBasic;
 
 namespace Microsoft.WebAssembly.Diagnostics
 {
@@ -475,14 +477,19 @@ public VarInfo[] GetLiveVarsAt(int offset)
 
     internal class TypeInfo
     {
+        private readonly ILogger logger;
         internal AssemblyInfo assembly;
         private TypeDefinition type;
         private List<MethodInfo> methods;
         internal int Token { get; }
         internal string Namespace { get; }
 
-        public TypeInfo(AssemblyInfo assembly, TypeDefinitionHandle typeHandle, TypeDefinition type)
+        public Dictionary<string, DebuggerBrowsableState?> DebuggerBrowsableFields = new();
+        public Dictionary<string, DebuggerBrowsableState?> DebuggerBrowsableProperties = new();
+
+        public TypeInfo(AssemblyInfo assembly, TypeDefinitionHandle typeHandle, TypeDefinition type, ILogger logger)
         {
+            this.logger = logger;
             this.assembly = assembly;
             var metadataReader = assembly.asmMetadataReader;
             Token = MetadataTokens.GetToken(metadataReader, typeHandle);
@@ -500,6 +507,63 @@ public TypeInfo(AssemblyInfo assembly, TypeDefinitionHandle typeHandle, TypeDefi
                 FullName = Namespace + "." + Name;
             else
                 FullName = Name;
+
+            foreach (var field in type.GetFields())
+            {
+                try
+                {
+                    var fieldDefinition = metadataReader.GetFieldDefinition(field);
+                    var fieldName = metadataReader.GetString(fieldDefinition.Name);
+                    AppendToBrowsable(DebuggerBrowsableFields, fieldDefinition.GetCustomAttributes(), fieldName);
+                }
+                catch (Exception ex)
+                {
+                    logger.LogDebug($"Failed to read browsable attributes of a field. ({ex.Message})");
+                    continue;
+                }
+            }
+
+            foreach (var prop in type.GetProperties())
+            {
+                try
+                {
+                    var propDefinition = metadataReader.GetPropertyDefinition(prop);
+                    var propName = metadataReader.GetString(propDefinition.Name);
+                    AppendToBrowsable(DebuggerBrowsableProperties, propDefinition.GetCustomAttributes(), propName);
+                }
+                catch (Exception ex)
+                {
+                    logger.LogDebug($"Failed to read browsable attributes of a property. ({ex.Message})");
+                    continue;
+                }
+            }
+
+            void AppendToBrowsable(Dictionary<string, DebuggerBrowsableState?> dict, CustomAttributeHandleCollection customAttrs, string fieldName)
+            {
+                foreach (var cattr in customAttrs)
+                {
+                    try
+                    {
+                        var ctorHandle = metadataReader.GetCustomAttribute(cattr).Constructor;
+                        if (ctorHandle.Kind != HandleKind.MemberReference)
+                            continue;
+                        var container = metadataReader.GetMemberReference((MemberReferenceHandle)ctorHandle).Parent;
+                        var valueBytes = metadataReader.GetBlobBytes(metadataReader.GetCustomAttribute(cattr).Value);
+                        var attributeName = metadataReader.GetString(metadataReader.GetTypeReference((TypeReferenceHandle)container).Name);
+                        if (attributeName != "DebuggerBrowsableAttribute")
+                            continue;
+                        var state = (DebuggerBrowsableState)valueBytes[2];
+                        if (!Enum.IsDefined(typeof(DebuggerBrowsableState), state))
+                            continue;
+                        dict.Add(fieldName, state);
+                        break;
+                    }
+                    catch
+                    {
+                        continue;
+                    }
+                }
+            }
         }
 
         public TypeInfo(AssemblyInfo assembly, string name)
@@ -515,7 +579,6 @@ public TypeInfo(AssemblyInfo assembly, string name)
         public override string ToString() => "TypeInfo('" + FullName + "')";
     }
 
-
     internal class AssemblyInfo
     {
         private static int next_id;
@@ -652,7 +715,7 @@ SourceFile FindSource(DocumentHandle doc, int rowid, string documentName)
             {
                 var typeDefinition = asmMetadataReader.GetTypeDefinition(type);
 
-                var typeInfo = new TypeInfo(this, type, typeDefinition);
+                var typeInfo = new TypeInfo(this, type, typeDefinition, logger);
                 TypesByName[typeInfo.FullName] = typeInfo;
                 TypesByToken[typeInfo.Token] = typeInfo;
                 if (pdbMetadataReader != null)
@@ -680,7 +743,6 @@ SourceFile FindSource(DocumentHandle doc, int rowid, string documentName)
                     }
                 }
             }
-
         }
 
         private void ProcessSourceLink()