added SkSL support for mustForceNegatedAtanParamToFloat cap

src/sksl/SkSLGLSLCodeGenerator.h

Index: src/sksl/SkSLGLSLCodeGenerator.h
diff --git a/src/sksl/SkSLGLSLCodeGenerator.h b/src/sksl/SkSLGLSLCodeGenerator.h
index 965721eb3136c6eae1f593cbbebd7779c8e54aff..17ac90ea233cae2f3dc1ffea9c38068e511f2378 100644
--- a/src/sksl/SkSLGLSLCodeGenerator.h
+++ b/src/sksl/SkSLGLSLCodeGenerator.h
@@ -55,6 +55,10 @@ struct GLCaps {
     bool fMustDeclareFragmentShaderOutput;
     // The Tegra3 compiler will sometimes never return if we have min(abs(x), y)
     bool fCanUseMinAndAbsTogether;
+    // On Intel GPU there is an issue where it misinterprets an atan argument (second argument only,
+    // apparently) of the form "-<expr>" as an int, so we rewrite it as "-1.0 * <expr>" to avoid
+    // this problem
+    bool fMustForceNegatedAtanParamToFloat;
 };
 
 /**