chore: move $effect visitors (#17041)

Author: Rich-Harris

packages/svelte/src/compiler/phases/3-transform/client/visitors/CallExpression.js

@@ -62,6 +62,17 @@ export function CallExpression(node, context) {
 				is_ignored(node, 'state_snapshot_uncloneable') && b.true
 			);
 
+		case '$effect':
+		case '$effect.pre': {
+			const callee = rune === '$effect' ? '$.user_effect' : '$.user_pre_effect';
+			const func = /** @type {Expression} */ (context.visit(node.arguments[0]));
+
+			const expr = b.call(callee, /** @type {Expression} */ (func));
+			expr.callee.loc = node.callee.loc; // ensure correct mapping
+
+			return expr;
+		}
+
 		case '$effect.root':
 			return b.call(
 				'$.effect_root',

packages/svelte/src/compiler/phases/3-transform/client/visitors/ExpressionStatement.js

@@ -11,16 +11,6 @@ export function ExpressionStatement(node, context) {
 	if (node.expression.type === 'CallExpression') {
 		const rune = get_rune(node.expression, context.state.scope);
 
-		if (rune === '$effect' || rune === '$effect.pre') {
-			const callee = rune === '$effect' ? '$.user_effect' : '$.user_pre_effect';
-			const func = /** @type {Expression} */ (context.visit(node.expression.arguments[0]));
-
-			const expr = b.call(callee, /** @type {Expression} */ (func));
-			expr.callee.loc = node.expression.callee.loc; // ensure correct mapping
-
-			return b.stmt(expr);
-		}
-
 		if (rune === '$inspect.trace') {
 			return b.empty;
 		}