Revert of added support for push_constant layout

src/sksl/SkSLSPIRVCodeGenerator.h

Index: src/sksl/SkSLSPIRVCodeGenerator.h
diff --git a/src/sksl/SkSLSPIRVCodeGenerator.h b/src/sksl/SkSLSPIRVCodeGenerator.h
index 6459e5bcf5d97e97cebd09c1bdf6fc272ef485e9..e6fc28ee0c5de4ae3cc55f261a44490ac1175820 100644
--- a/src/sksl/SkSLSPIRVCodeGenerator.h
+++ b/src/sksl/SkSLSPIRVCodeGenerator.h
@@ -14,7 +14,6 @@
 #include <unordered_map>
 
 #include "SkSLCodeGenerator.h"
-#include "SkSLMemoryLayout.h"
 #include "ir/SkSLBinaryExpression.h"
 #include "ir/SkSLBoolLiteral.h"
 #include "ir/SkSLConstructor.h"
@@ -64,7 +63,6 @@
 
     SPIRVCodeGenerator(const Context* context)
     : fContext(*context)
-    , fDefaultLayout(MemoryLayout::k140_Standard)
     , fCapabilities(1 << SpvCapabilityShader)
     , fIdCount(1)
     , fBoolTrue(0)
@@ -95,22 +93,17 @@
 
     SpvId getType(const Type& type);
 
-    SpvId getType(const Type& type, const MemoryLayout& layout);
-
     SpvId getFunctionType(const FunctionDeclaration& function);
 
     SpvId getPointerType(const Type& type, SpvStorageClass_ storageClass);
 
-    SpvId getPointerType(const Type& type, const MemoryLayout& layout, 
-                         SpvStorageClass_ storageClass);
-
     std::vector<SpvId> getAccessChain(const Expression& expr, std::ostream& out);
 
     void writeLayout(const Layout& layout, SpvId target);
 
     void writeLayout(const Layout& layout, SpvId target, int member);
 
-    void writeStruct(const Type& type, const MemoryLayout& layout, SpvId resultId);
+    void writeStruct(const Type& type, SpvId resultId);
 
     void writeProgramElement(const ProgramElement& pe, std::ostream& out);
 
@@ -236,7 +229,6 @@
                           std::ostream& out);
 
     const Context& fContext;
-    const MemoryLayout fDefaultLayout;
 
     uint64_t fCapabilities;
     SpvId fIdCount;