Revert of TextRun::length() should return an unsigned

Source/platform/fonts/shaping/HarfBuzzShaper.cpp

Index: Source/platform/fonts/shaping/HarfBuzzShaper.cpp
diff --git a/Source/platform/fonts/shaping/HarfBuzzShaper.cpp b/Source/platform/fonts/shaping/HarfBuzzShaper.cpp
index cf3a64849a1e544d4c87406e329c6edd00c4bd85..bcf441c52f205f331c6ae205cf4aa08369f9f3f3 100644
--- a/Source/platform/fonts/shaping/HarfBuzzShaper.cpp
+++ b/Source/platform/fonts/shaping/HarfBuzzShaper.cpp
@@ -445,8 +445,9 @@
 }
 
 
-void HarfBuzzShaper::setDrawRange(unsigned from, unsigned to)
-{
+void HarfBuzzShaper::setDrawRange(int from, int to)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(from >= 0);
     ASSERT_WITH_SECURITY_IMPLICATION(to <= m_run.length());
     m_fromIndex = from;
     m_toIndex = to;