remove .m flag on component context

Author: Rich-Harris

packages/svelte/src/internal/client/context.js

@@ -144,7 +144,6 @@ export function push(props, runes = false, fn) {
 		c: null,
 		d: false,
 		e: null,
-		m: false,
 		s: props,
 		x: null,
 		l: null

packages/svelte/src/internal/client/reactivity/effects.js

@@ -182,10 +182,7 @@ export function user_effect(fn) {
 	// Non-nested `$effect(...)` in a component should be deferred
 	// until the component is mounted
 	var defer =
-		active_effect !== null &&
-		(active_effect.f & BRANCH_EFFECT) !== 0 &&
-		component_context !== null &&
-		!component_context.m;
+		active_effect !== null && (active_effect.f & BRANCH_EFFECT) !== 0 && active_reaction === null;
 
 	if (DEV) {
 		define_property(fn, 'name', {

packages/svelte/src/internal/client/types.d.ts

@@ -18,8 +18,6 @@ export type ComponentContext = {
 	d: boolean;
 	/** deferred effects */
 	e: null | Array<() => void | (() => void)>;
-	/** mounted */
-	m: boolean;
 	/**
 	 * props — needed for legacy mode lifecycle functions, and for `createEventDispatcher`
 	 * @deprecated remove in 6.0