diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index 19c6a7935..f1c34c8ac 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -9348,10 +9348,6 @@ declare var IDBDatabase: {
     new(): IDBDatabase;
 };
 
-interface IDBEnvironment {
-    readonly indexedDB: IDBFactory;
-}
-
 /** In the following code snippet, we make a request to open a database, and include handlers for the success and error cases. For a full working example, see our To-do Notifications app (view example live.) */
 interface IDBFactory {
     /**
@@ -18533,12 +18529,10 @@ interface WindowEventMap extends GlobalEventHandlersEventMap, WindowEventHandler
 }
 
 /** A window containing a DOM document; the document property points to the DOM document loaded in that window. */
-interface Window extends EventTarget, AnimationFrameProvider, GlobalEventHandlers, IDBEnvironment, WindowBase64, WindowConsole, WindowEventHandlers, WindowLocalStorage, WindowOrWorkerGlobalScope, WindowSessionStorage {
+interface Window extends EventTarget, AnimationFrameProvider, GlobalEventHandlers, WindowConsole, WindowEventHandlers, WindowLocalStorage, WindowOrWorkerGlobalScope, WindowSessionStorage {
     readonly applicationCache: ApplicationCache;
-    readonly caches: CacheStorage;
     readonly clientInformation: Navigator;
     readonly closed: boolean;
-    readonly crypto: Crypto;
     customElements: CustomElementRegistry;
     defaultStatus: string;
     readonly devicePixelRatio: number;
@@ -18603,7 +18597,6 @@ interface Window extends EventTarget, AnimationFrameProvider, GlobalEventHandler
     readonly pageXOffset: number;
     readonly pageYOffset: number;
     readonly parent: Window;
-    readonly performance: Performance;
     readonly personalbar: BarProp;
     readonly screen: Screen;
     readonly screenLeft: number;
@@ -18667,11 +18660,6 @@ declare var Window: {
     new(): Window;
 };
 
-interface WindowBase64 {
-    atob(encodedString: string): string;
-    btoa(rawString: string): string;
-}
-
 interface WindowConsole {
     readonly console: Console;
 }
@@ -19533,10 +19521,8 @@ declare var Option: {
     new(text?: string, value?: string, defaultSelected?: boolean, selected?: boolean): HTMLOptionElement;
 };
 declare var applicationCache: ApplicationCache;
-declare var caches: CacheStorage;
 declare var clientInformation: Navigator;
 declare var closed: boolean;
-declare var crypto: Crypto;
 declare var customElements: CustomElementRegistry;
 declare var defaultStatus: string;
 declare var devicePixelRatio: number;
@@ -19601,7 +19587,6 @@ declare var outerWidth: number;
 declare var pageXOffset: number;
 declare var pageYOffset: number;
 declare var parent: Window;
-declare var performance: Performance;
 declare var personalbar: BarProp;
 declare var screen: Screen;
 declare var screenLeft: number;
@@ -19926,9 +19911,6 @@ declare var onvolumechange: ((this: Window, ev: Event) => any) | null;
  */
 declare var onwaiting: ((this: Window, ev: Event) => any) | null;
 declare var onwheel: ((this: Window, ev: WheelEvent) => any) | null;
-declare var indexedDB: IDBFactory;
-declare function atob(encodedString: string): string;
-declare function btoa(rawString: string): string;
 declare function cancelAnimationFrame(handle: number): void;
 declare function requestAnimationFrame(callback: FrameRequestCallback): number;
 declare var caches: CacheStorage;
@@ -19946,8 +19928,6 @@ declare function fetch(input: RequestInfo, init?: RequestInit): Promise<Response
 declare function queueMicrotask(callback: VoidFunction): void;
 declare function setInterval(handler: TimerHandler, timeout?: number, ...arguments: any[]): number;
 declare function setTimeout(handler: TimerHandler, timeout?: number, ...arguments: any[]): number;
-declare var sessionStorage: Storage;
-declare var localStorage: Storage;
 declare var onafterprint: ((this: Window, ev: Event) => any) | null;
 declare var onbeforeprint: ((this: Window, ev: Event) => any) | null;
 declare var onbeforeunload: ((this: Window, ev: BeforeUnloadEvent) => any) | null;
diff --git a/inputfiles/addedTypes.json b/inputfiles/addedTypes.json
index 7f8330620..9ac2f163e 100644
--- a/inputfiles/addedTypes.json
+++ b/inputfiles/addedTypes.json
@@ -296,10 +296,7 @@
                         }
                     }
                 },
-                "extends": "SVGElement",
-                "implements": [
-                    "SVGFilterPrimitiveStandardAttributes"
-                ]
+                "extends": "SVGElement"
             },
             "AbortSignal": {
                 "events": {
@@ -1063,9 +1060,7 @@
             },
             "SVGElement": {
                 "implements": [
-                    "ElementCSSInlineStyle",
-                    "GlobalEventHandlers",
-                    "DocumentAndElementEventHandlers"
+                    "ElementCSSInlineStyle"
                 ]
             },
             "Text": {
diff --git a/inputfiles/removedTypes.json b/inputfiles/removedTypes.json
index 174885a7e..f2503bb34 100644
--- a/inputfiles/removedTypes.json
+++ b/inputfiles/removedTypes.json
@@ -313,11 +313,14 @@
                 "properties": {
                     "property": {
                         "browser": null,
+                        "caches": null,
+                        "crypto": null,
                         "msCredentials": null,
                         "ontouchcancel": null,
                         "ontouchend": null,
                         "ontouchmove": null,
-                        "ontouchstart": null
+                        "ontouchstart": null,
+                        "performance": null
                     }
                 },
                 "methods": {
@@ -328,6 +331,8 @@
                 },
                 "implements": [
                     "GlobalFetch",
+                    "IDBEnvironment",
+                    "WindowBase64",
                     "WindowTimers"
                 ]
             },
diff --git a/src/emitter.ts b/src/emitter.ts
index 144ba91a5..72c4bfb67 100644
--- a/src/emitter.ts
+++ b/src/emitter.ts
@@ -870,9 +870,10 @@ export function emitWebIdl(webidl: Browser.WebIdl, flavor: Flavor) {
 
         printer.print(`interface ${getNameWithTypeParameter(i, processedIName)}`);
 
-        const finalExtends = distinct([i.extends || "Object"].concat((i.implements || []).sort())
+        const finalExtends = [i.extends || "Object"]
+            .concat((i.implements || []).sort())
             .filter(i => i !== "Object")
-            .map(processIName));
+            .map(processIName);
 
         if (finalExtends.length) {
             printer.print(` extends ${finalExtends.join(", ")}`);
diff --git a/src/index.ts b/src/index.ts
index e16e2998c..0da4f6e6c 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -166,11 +166,12 @@ function emitDom() {
         for (const include of w.includes) {
             const target = webidl.interfaces!.interface[include.target];
             if (target) {
-                if (target.implements) {
-                    target.implements.push(include.includes);
-                }
-                else {
+                if (!target.implements) {
                     target.implements = [include.includes];
+                } else if (!target.implements.includes(include.includes)) {
+                    // This makes sure that browser.webidl.preprocessed.json
+                    // does not already have the mixin reference
+                    target.implements.push(include.includes);
                 }
             }
         }