Classify this in parameter position as a keyword

src/services/services.ts

@@ -7533,7 +7533,8 @@ namespace ts {
                                 return;
                             case SyntaxKind.Parameter:
                                 if ((<ParameterDeclaration>token.parent).name === token) {
-                                    return ClassificationType.parameterName;
+                                    const isThis = token.kind === SyntaxKind.Identifier && (<Identifier>token).originalKeywordKind === SyntaxKind.ThisKeyword;
+                                    return isThis ? ClassificationType.keyword : ClassificationType.parameterName;
                                 }
                                 return;
                         }

tests/cases/fourslash/classifyThisParameter.ts

@@ -0,0 +1,13 @@
+/// <reference path="fourslash.ts"/>
+
+////function f(this){}
+
+var c = classification;
+verify.syntacticClassificationsAre(
+    c.keyword("function"),
+    c.identifier("f"),
+    c.punctuation("("),
+    c.keyword("this"),
+    c.punctuation(")"),
+    c.punctuation("{"),
+    c.punctuation("}"));