Replace use of GrTHashTable in GrFontCache with SkTDynamicHash.

src/core/SkDescriptor.h

Index: src/core/SkDescriptor.h
diff --git a/src/core/SkDescriptor.h b/src/core/SkDescriptor.h
index c526451af5e68e80ff44253f0dde89a7cef457b1..d550863568ef16e569c742d8fd50c099c1061537 100644
--- a/src/core/SkDescriptor.h
+++ b/src/core/SkDescriptor.h
@@ -123,7 +123,7 @@ private:
     static uint32_t ComputeChecksum(const SkDescriptor* desc) {
         const uint32_t* ptr = (const uint32_t*)desc + 1; // skip the checksum field
         size_t len = desc->fLength - sizeof(uint32_t);
-        return SkChecksum::Compute(ptr, len);
+        return SkChecksum::Murmur3(ptr, len);
     }
 
     // private so no one can create one except our factories