ES31: Implement gl_in in Geometry Shader

This patch intends to implement geometry shader built-in interface
block instance gl_in defined in GL_OES_geometry_shader.

1. Add the definition of gl_in and its interface block gl_PerVertex
   into the symbol table.
2. Support gl_Position as a member of gl_in.
3. Set the array size of gl_in when a valid input primitive type is
   known.
4. Add check that it should be a compile error to index gl_in or
   call length() on gl_in without a valid input primitive declaration.

This patch also adds unit tests to cover all these new features.

BUG=angleproject:1941
TEST=angle_unittests

Change-Id: I8da20c943b29c9ce904834625b396aab6302e1e1
Reviewed-on: https://chromium-review.googlesource.com/605059
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/ParseContext.h b/src/compiler/translator/ParseContext.h
index 0ea5535..e9b2c08 100644
--- a/src/compiler/translator/ParseContext.h
+++ b/src/compiler/translator/ParseContext.h
@@ -535,6 +535,7 @@
     bool checkPrimitiveTypeMatchesTypeQualifier(const TTypeQualifier &typeQualifier);
     bool parseGeometryShaderInputLayoutQualifier(const TTypeQualifier &typeQualifier);
     bool parseGeometryShaderOutputLayoutQualifier(const TTypeQualifier &typeQualifier);
+    void setGeometryShaderInputArraySizes();
 
     // Set to true when the last/current declarator list was started with an empty declaration. The
     // non-empty declaration error check will need to be performed if the empty declaration is
@@ -600,6 +601,8 @@
     int mGeometryShaderMaxVertices;
     int mMaxGeometryShaderInvocations;
     int mMaxGeometryShaderMaxVertices;
+    int mGeometryShaderInputArraySize;  // Track if all input array sizes are same and matches the
+                                        // latter input primitive declaration.
 };
 
 int PaParseStrings(size_t count,