Add IndexType parameter to GrDrawTarget::drawPaths

Allows the caller to decide whether they sent 8, 16, or 32 bit path
indices.

BUG=skia:

Review URL: https://codereview.chromium.org/746253003
diff --git a/src/gpu/GrStencilAndCoverTextContext.cpp b/src/gpu/GrStencilAndCoverTextContext.cpp
index d70593e..d6efe98 100644
--- a/src/gpu/GrStencilAndCoverTextContext.cpp
+++ b/src/gpu/GrStencilAndCoverTextContext.cpp
@@ -367,9 +367,9 @@
         return;
     }
 
-    fDrawTarget->drawPaths(&fDrawState, fGlyphs, fIndexBuffer, fPendingGlyphCount, fTransformBuffer,
-                           GrPathRendering::kTranslate_PathTransformType,
-                           GrPathRendering::kWinding_FillType);
+    fDrawTarget->drawPaths(&fDrawState, fGlyphs, fIndexBuffer, GrPathRange::kU16_PathIndexType,
+                           fTransformBuffer, GrPathRendering::kTranslate_PathTransformType,
+                           fPendingGlyphCount, GrPathRendering::kWinding_FillType);
 
     fPendingGlyphCount = 0;
 }