removed const from ASTVarDeclaration::fName to avoid a Chromium build failure

src/sksl/ast/SkSLASTVarDeclaration.h

Index: src/sksl/ast/SkSLASTVarDeclaration.h
diff --git a/src/sksl/ast/SkSLASTVarDeclaration.h b/src/sksl/ast/SkSLASTVarDeclaration.h
index 2eaf4982ffb969402aab07ca68de4387fd5f971b..066922fb852b7271d7c2bc8329b15c5367938f37 100644
--- a/src/sksl/ast/SkSLASTVarDeclaration.h
+++ b/src/sksl/ast/SkSLASTVarDeclaration.h
@@ -44,7 +44,7 @@ struct ASTVarDeclaration {
         return result;        
     }
 
-    const std::string fName;
+    std::string fName;
 
     // array sizes, if any. e.g. 'foo[3][]' has sizes [3, null]
     std::vector<std::unique_ptr<ASTExpression>> fSizes;