Fix incorrect indices for emphasis marks drawing in InlineTextBox::paint

LayoutTests/fast/text/emphasis-combined-text.html

Index: LayoutTests/fast/text/emphasis-combined-text.html
diff --git a/LayoutTests/fast/text/emphasis-combined-text.html b/LayoutTests/fast/text/emphasis-combined-text.html
index 91ebfec48afcdf51f047260b09b037d98d769772..46d5c74a953f0340762112007275fe8d0b1446ac 100644
--- a/LayoutTests/fast/text/emphasis-combined-text.html
+++ b/LayoutTests/fast/text/emphasis-combined-text.html
@@ -2,6 +2,7 @@
 <style>
 html {
     -webkit-writing-mode: vertical-rl;
+    text-rendering: geometricPrecision;
 }
 
 p {
@@ -15,11 +16,11 @@ p {
 
 </style>
 <p>
-    <span  style="-webkit-text-emphasis: sesame red">文字<span class="combine">900</span>年</span>
+    <span  style="-webkit-text-emphasis: sesame red">文字<span class="combine">90</span>年</span>
 </p>
 <p>
-    <span  style="-webkit-text-emphasis: '@' red">文字<span class="combine">900</span>年</span>
+    <span  style="-webkit-text-emphasis: '@' red">文字<span class="combine">90</span>年</span>
 </p>
 <p>
-    <span  style="-webkit-text-emphasis: '年' red">文字<span class="combine">900</span>年</span>
+    <span  style="-webkit-text-emphasis: '年' red">文字<span class="combine">90</span>年</span>
 </p>