Separate CompilationInfo into its own file.

src/compiler/code-generator.h

Index: src/compiler/code-generator.h
diff --git a/src/compiler/code-generator.h b/src/compiler/code-generator.h
index 8ad943165369258ac178ca17ef96f2c64018f3de..22ba727983170eceb4583eb527b8f7b3b52ae374 100644
--- a/src/compiler/code-generator.h
+++ b/src/compiler/code-generator.h
@@ -5,7 +5,6 @@
 #ifndef V8_COMPILER_CODE_GENERATOR_H_
 #define V8_COMPILER_CODE_GENERATOR_H_
 
-#include "src/compiler.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/instruction.h"
 #include "src/compiler/unwinding-info-writer.h"
@@ -16,6 +15,9 @@
 
 namespace v8 {
 namespace internal {
+
+class CompilationInfo;
+
 namespace compiler {
 
 // Forward declarations.
@@ -58,7 +60,7 @@ class CodeGenerator final : public GapResolver::Assembler {
   InstructionSequence* code() const { return code_; }
   FrameAccessState* frame_access_state() const { return frame_access_state_; }
   const Frame* frame() const { return frame_access_state_->frame(); }
-  Isolate* isolate() const { return info_->isolate(); }
+  Isolate* isolate() const;
   Linkage* linkage() const { return linkage_; }
 
   Label* GetLabel(RpoNumber rpo) { return &labels_[rpo.ToSize()]; }