Update version to 7.4

TBR=machenbach@chromium.org
NOTRY=true

Change-Id: I2505fb40aa13a361277eaf9ec2c88cea249079da
Reviewed-on: https://chromium-review.googlesource.com/c/1433785
Commit-Queue: Michael Hablich <hablich@chromium.org>
Reviewed-by: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59060}

include/v8-version.h

@@ -9,7 +9,7 @@
 // NOTE these macros are used by some of the tool scripts and the build
 // system so their names cannot be changed without changing the scripts.
 #define V8_MAJOR_VERSION 7
-#define V8_MINOR_VERSION 3
+#define V8_MINOR_VERSION 4
 #define V8_BUILD_NUMBER 0
 #define V8_PATCH_LEVEL 0