fix collapsing html with static contents

[tanhauhau]

Fixes #5040

• we collapsed text nodes for optimisation

svelte/src/compiler/compile/render_dom/wrappers/Fragment.ts

Lines 101 to 103 in 926a2ae

	if (last_child && last_child.node.type === 'Text') {
	(last_child as Text).data = data + (last_child as Text).data;
	continue;

so, we should use TextWrapper#data instead of TextWrapper#node.data

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