LibHTML: Collapse all-whitespace LayoutText into a single ' ' char.

LibHTML/Dump.cpp

@@ -38,7 +38,7 @@ void dump_tree(const LayoutNode& node)
         printf("   ");
     printf("%s{%p}", node.class_name(), &node);
     if (node.is_text())
-        printf(" \"%s\"", static_cast<const LayoutText&>(node).node().data().characters());
+        printf(" \"%s\"", static_cast<const LayoutText&>(node).text().characters());
     printf("\n");
     ++indent;
     node.for_each_child([](auto& child) {

LibHTML/LayoutText.cpp

@@ -1,4 +1,5 @@
 #include <LibHTML/LayoutText.h>
+#include <ctype.h>
 
 LayoutText::LayoutText(const Text& text)
     : LayoutNode(&text)
@@ -8,3 +9,20 @@ LayoutText::LayoutText(const Text& text)
 LayoutText::~LayoutText()
 {
 }
+
+static bool is_all_whitespace(const String& string)
+{
+    for (int i = 0; i < string.length(); ++i) {
+        if (!isspace(string[i]))
+            return false;
+    }
+    return true;
+}
+
+const String& LayoutText::text() const
+{
+    static String one_space = " ";
+    if (is_all_whitespace(node().data()))
+        return one_space;
+    return node().data();
+}

LibHTML/LayoutText.h

@@ -10,6 +10,8 @@ public:
 
     const Text& node() const { return static_cast<const Text&>(*LayoutNode::node()); }
 
+    const String& text() const;
+
     virtual const char* class_name() const override { return "LayoutText"; }
     virtual bool is_text() const final { return true; }