Don't create empty vectors using SubVector.

src/strtod.cc

Index: src/strtod.cc
diff --git a/src/strtod.cc b/src/strtod.cc
index 76e2bc4a06d83c6ad95ce493c88833a8fb527cd5..0ed1b0d914791280dea19a54837ebc6673f164ec 100644
--- a/src/strtod.cc
+++ b/src/strtod.cc
@@ -128,7 +128,7 @@ static Vector<const char> TrimLeadingZeros(Vector<const char> buffer) {
       return buffer.SubVector(i, buffer.length());
     }
   }
-  return buffer.SubVector(0, 0);
+  return Vector<const char>(buffer.start(), 0);
 }
 
 
@@ -138,7 +138,7 @@ static Vector<const char> TrimTrailingZeros(Vector<const char> buffer) {
       return buffer.SubVector(0, i + 1);
     }
   }
-  return buffer.SubVector(0, 0);
+  return Vector<const char>(buffer.start(), 0);
 }