Fix MSVC warnings about possible value truncation.

src/cff.cc

Index: src/cff.cc
diff --git a/src/cff.cc b/src/cff.cc
index a9368df5efe0cbc6980e62aa301249a74ba6d027..7866614ced2cf27830be5bcf83ec01064008efad 100644
--- a/src/cff.cc
+++ b/src/cff.cc
@@ -472,7 +472,7 @@ bool ParseDictData(const uint8_t *data, size_t table_length,
 
     FONT_FORMAT font_format = FORMAT_UNKNOWN;
     bool have_ros = false;
-    size_t glyphs = 0;
+    uint16_t glyphs = 0;
     size_t charset_offset = 0;
 
     while (table.offset() < dict_length) {
@@ -692,7 +692,7 @@ bool ParseDictData(const uint8_t *data, size_t table_length,
             return OTS_FAILURE();
           }
           if (format == 0) {
-            for (size_t j = 0; j < glyphs; ++j) {
+            for (uint16_t j = 0; j < glyphs; ++j) {
               uint8_t fd_index = 0;
               if (!table.ReadU8(&fd_index)) {
                 return OTS_FAILURE();
@@ -836,7 +836,7 @@ bool ParseDictData(const uint8_t *data, size_t table_length,
       }
       switch (format) {
         case 0:
-          for (unsigned j = 1 /* .notdef is omitted */; j < glyphs; ++j) {
+          for (uint16_t j = 1 /* .notdef is omitted */; j < glyphs; ++j) {
             uint16_t sid = 0;
             if (!table.ReadU16(&sid)) {
               return OTS_FAILURE();