Fix and enable warning C4244 (Conversion from 'type1' to 'type2', possible loss of data)

Change-Id: I73d9a2b9ad16f032be974b9c819de0dc1247c2ea
Reviewed-on: https://chromium-review.googlesource.com/264533
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/IndexRangeCache.cpp b/src/libANGLE/renderer/IndexRangeCache.cpp
index 4a71cf4..84017b6 100644
--- a/src/libANGLE/renderer/IndexRangeCache.cpp
+++ b/src/libANGLE/renderer/IndexRangeCache.cpp
@@ -100,7 +100,7 @@
 }
 
 IndexRangeCache::IndexRange::IndexRange(GLenum typ, intptr_t off, GLsizei c)
-    : type(typ), offset(off), count(c)
+    : type(typ), offset(static_cast<unsigned int>(off)), count(c)
 {
 }