Completions for asserts and declare (#36355)

* Add completions for `asserts`

* Add declare assertions.

src/harness/fourslashInterfaceImpl.ts

@@ -902,7 +902,7 @@ namespace FourSlashInterface {
         export const keywords: readonly ExpectedCompletionEntryObject[] = keywordsWithUndefined.filter(k => k.name !== "undefined");
 
         export const typeKeywords: readonly ExpectedCompletionEntryObject[] =
-            ["false", "null", "true", "void", "any", "boolean", "keyof", "never", "readonly", "number", "object", "string", "symbol", "undefined", "unique", "unknown", "bigint"].map(keywordEntry);
+            ["false", "null", "true", "void", "asserts", "any", "boolean", "keyof", "never", "readonly", "number", "object", "string", "symbol", "undefined", "unique", "unknown", "bigint"].map(keywordEntry);
 
         const globalTypeDecls: readonly ExpectedCompletionEntryObject[] = [
             interfaceEntry("Symbol"),
@@ -1058,7 +1058,7 @@ namespace FourSlashInterface {
         }
 
         export const classElementKeywords: readonly ExpectedCompletionEntryObject[] =
-            ["private", "protected", "public", "static", "abstract", "async", "constructor", "get", "readonly", "set"].map(keywordEntry);
+            ["private", "protected", "public", "static", "abstract", "async", "constructor", "declare", "get", "readonly", "set"].map(keywordEntry);
 
         export const classElementInJsKeywords = getInJsKeywords(classElementKeywords);
 
@@ -1152,6 +1152,7 @@ namespace FourSlashInterface {
             "let",
             "package",
             "yield",
+            "asserts",
             "any",
             "async",
             "await",
@@ -1351,6 +1352,7 @@ namespace FourSlashInterface {
             "let",
             "package",
             "yield",
+            "asserts",
             "any",
             "async",
             "await",

src/services/completions.ts

@@ -2525,6 +2525,7 @@ namespace ts.Completions {
             case SyntaxKind.GetKeyword:
             case SyntaxKind.SetKeyword:
             case SyntaxKind.AsyncKeyword:
+            case SyntaxKind.DeclareKeyword:
                 return true;
             default:
                 return isClassMemberModifier(kind);

src/services/utilities.ts

@@ -1283,6 +1283,7 @@ namespace ts {
 
     export const typeKeywords: readonly SyntaxKind[] = [
         SyntaxKind.AnyKeyword,
+        SyntaxKind.AssertsKeyword,
         SyntaxKind.BigIntKeyword,
         SyntaxKind.BooleanKeyword,
         SyntaxKind.FalseKeyword,